I have a black/white/ground wire coming from my power supply into my bathroom. I want to install a 274w combination device so as I can have one plug outlet and a switch for the shower fan.I need to see a diagram to correctly hook up my power wire and the wire going up to the fan

Is this a new bidet installation, USA? What year was home built and/ or remodeled?

It's probably safe but It would not be wise to use the unit without GFCI protection.

Please describe the installation. Is it plugged into a bathroom circuit with a GFCI breaker in the house panel or is there a GFCI receptacle protecting multiple outlets in the bathroom.

The typical cause for GFCI nuisance trips is an improper connection of protective equipment ground and neutral (grounded conductor) somewhere downstream of the GFCI protection device. IOTWs, a white neutral wire is touching bare ground wire or metal box.

You might try plugging the bidet into a long 3 wire extension cord so you can try a different GFCI outlet... in the kitchen or dining room. If it works at different GFCI circuits then likely it's not the unit but rather the bathroom wiring.

Comment below for further assistance.

Bit more information is needed.
Wire color is not as important as knowing what wire is for.
Knowing Hot black hot wire is good step.
Next, see if box has neutral wires. Neutrals are usually white wires that are twisted together and covered with wire nut. Test black hot to each white wire to find neutral.
If box does not have neutrals, then this device cannot be wired to code.
Other black wire probably goes to light.

Open following link for illustration of wiring:
http://waterheatertimer.org/How-to-wire-combination-switch-outlet.html

Yes. For each half of the device there will be two terminals, plus one ground terminal. (total 5) For the receptacle, one terminal will be brass and the other will be silver. These two terminals will be on opposite sides of the receptacle, but both will be nearest the receptacle end. The other two terminals are for the switch, and their color is not important. You must place a jumper wire from the brass terminal of the receptacle to the nearest terminal of the switch. There might already be a tab connecting these two terminals together - if so, then you don't need the jumper, just tighten down these two screws. You will wire your incoming black wire to the other switch terminal. Your white wire goes to the remaining terminal which is for the receptacle and will be silver. Your ground wire goes to the green ground terminal. Good luck, Al K

First you have to identify cables.
You have 2 cables that enter box. Each cable has black and white wires.
One cable probably comes from breaker box, and one cable probably goes to Load (which means your fan-light)

Separate wires for testing. Turn power ON.
Test each wire to bare ground wire. Tester lights up on Hot wire. This wire will connect to brass 'Line' screw on back of new GFCI device.
Hot is identified. Test Hot to all other wires except bare ground. Tester lights up on Neutral wire. Neutral connects to silver screw that sits across from Line screw on new GFCI device.
Other two wires inside box go to Load.
These wires connect to the two wires that stick out on back of new GFCI device.

Ground wires are connected together and connect to green screw on new device.

Ok you have GFCI combination switch-plug.

Wires coming out of back of device are connected to "Load" wires.
Load are the black and white wires that go to fan, light, motor.

The black and white wires coming from circuit breaker connect to terminals marked "Line"
Look at back of device for markings.
Black wire from breaker goes to brass screw, white wire goes to silver screw.

There is one more set of screws on device. Device usually arrives with tape over these two screws.
This is what those screws are for: If you are working in a junction box, then three cables enter box.
One cable is for Line wires from breaker box.
Second cable goes to Load (light-fan-motor) that is controlled by switch.
Third cable goes forward to another switch or outlet >> and those wires connect to last set of screws on combo device. Black to brass and white to silver.

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The 2 whites from the Romex cable go together along with a jumper. Now, the neutral jumper from the white bundle goes to the SILVER screw terminal one the side of the outlet where the LONGER slot is.

The black wire (load/light side), goes to the brass screw terminal on the SAME side outlet.

The OTHER black (line/HOT) wire goes to the opposite side of the switch, the side that has the connecting tab.

The grounding wires go together and then get connected to the box ground.

You are replacing old switch-receptacle device.
New device also has switch and receptacle.
You want switch to control light, but not receptacle.
You want receptacle 'hot' all the time.

You have 2 cables that enter box.
Each cable has white, black and ground wires.
Ground wires are twisted together and attached to green ground screws and not discussed more.

Screws on new device:
Side 1 of device: New device has dark screw(s) or brass screws on one side ... these screws are connected together by brass plate. This side is the Hot side of device.

Side 2 of device: Other side has 2 separate and unconnected screws. These screws are not connected in any way. Each of the 2 disconnected screws sits opposite the switch and opposite the plug.

Cables.
One cable comes from breaker box. This cable has a Hot and Neutral wire. The Hot is black. Neutral is white.
The other cable goes to Load (light). Black supplies power to Load (light), and white connects to Neutral.
If you are uncertain which is which, testing is shown below.

Connect the device:
Side 1 of device: Black Hot goes to dark colored screw(s) that are connected by brass plate. (This is only wire connected to this side of device)
Side 2 of device: Black that goes to Load (light) connects to screw that sits opposite the switch.
Side 2 of device: White Neutral connects to screw that sits opposite the plug

One wire is left .. the white from light. This white wire connects to white Neutral wire. Since white neutral is already connected to device, look on back of device to see if there is a quick-connect hole for you to shove wire into back of device. If device doesn't have quick-connect, then twist white wires together, and add a short jumper wire to device, and then all the whites are connected to neutral. Circuit is complete.

How to test for Hot and Neutral
Separate wires.
Turn on power.
Test each wire to bare ground.
Tester lights up on hot wire.
Now test hot wire to other wires.
Tester lights up on neutral

There are more than a few ways to wire this device. The switch box where the device is installed _must_ have a neutral wire for the receptacle to work. This is usually a white wire.

The switch box should have at least 2 cables in it. One cable is the incoming HOT(black) and neutral(white) from the circuit breaker panel (or source). The second cable is the outgoing switch leg(black) and neutral(white) to the light. Each cable should have a bare equipment grounding wire.

The most common way to install this device is to connect the hot wire to one of the black screws, pick one. ( I'm assuming that you have _not_ removed the brass tab between the 2 black screws.)

The 2 neutral (white) wires are twisted together under a wirenut along with a pigtail which connects to the silver screw on the device.

The black wire that goes to the light (switch leg) is then connected to the brass or gold screw.

The bare ground wires are twisted together under a wirenut along with a pigtail which is connected to the green screw.

Switch has 2 black wires. One black is hot wire. One black is wire going to fan. Turn off power. Remove wires from switch and separate. Turn power back on. Using ordinary tester, test each black wire to bare copper ground wire. Only one of the black wires will test hot. The other black wire goes to fan.
Timer black wire connects to black hot
Timer blue wire connects to black wire going to fan
Timer white wire connects to white neutral (in absence of white neutral, connect Timer white wire to bare ground)
Timer green connects to bare ground wire

Black to gold, wht to silver grnd to green