In trying to connect my Coby headset mic to my computer, I note that the Coby headphone jack is green, whereas the headphone input on my Dell desktop computer is blue. Does this make a difference? Thanks!

How to set up the headphone with mic attachment and my destop speakers are are seperately
How to Hook Up a Microphone and Headset to a Computer
In the past, business professionals used telephones to conference with customers or employees, but applications like Skype have made it simple for all users to voice and video chat with one another long-distance. Having a good audio configuration is critical for workers who often need to touch base with clients or other business professionals. Headsets allow users to both listen to and talk to others hands-free, but sometimes the mouthpieces attached to a headset aren't of the best quality. You can connect the speakers on the headset to the computer but hook up a separate microphone to the PC to use instead of the headset's mouthpiece.
1.
Plug the headphone connector on the headset to the green-colored jack on the back of the desktop PC or into the headphone jack on the right or left side of the laptop or netbook.
2.
Connect the microphone to the pink-colored jack on the back of the desktop computer or into the mic jack on the right or left side of the laptop or netbook.
3.
Click "Start ' Control Panel ' Hardware and Sound ' Sound." Select the headset on the Playback tab and then click "Set Default" to use it instead of the computer speakers. Click "OK."

The Z11 has a four-pole input/output plug to connect the mic and the earphone. The earphone needs to be connected to the earphone jack and the mic needs to be connected to the mic input jack on the back of the computer. In other words, you should have to 3.5 mm plugs. Plugging both into the same jack will disconnect one or the other. Check your adapter, It should have two separate 3.5mm plugs. If it does, be sure they are connected to the right jacks on the computer. The headphone jack will have a headphone symbol; the mic jack will have a microphone symbol. Go to System Preferences, Sound. Select the line in preference for input and the line out preference for headphones. Just may work.

Try downloading latest Real Tek Drivers

The headphone plug goes into the green jack on the computer. The mic plug goes into the red jack on the computer. The headphone plug with have three segments on the jack, the mic plug will have two, and they'll both be marked. If you're computer doesn't have color jacks, the mic will go into the one with a picture of a mic, the headphones will go into the one with a picture of a headphone or speaker.

When you insert the headphone jack into the "audio-output" jack,
which should be GREEN coloured, it should mechanically disable the built-in speakers. If that does not happen, you're connecting it to the wrong socket.

Be sure to insert the microphone's jack into the PINK socket, which is the "microphone-input" socket.

I guess you are referring to a Head phone and microphone set, with the cable splitting at the other end into two jacks. Most probably one a pink (or rose) colored one and the other green colored. Not necessary though, sometimes these two can be same color with indentation on the plastic surface to identify which one is Microphone and Headphone. If this is what the information you are looking for look on the back side of the computer. You will see three sockets in one column. If the computer is relatively new chances are that the surrounding area of these three jacks are also colored pink, green and blue. Match the pink jack to the pink (head phone) socket. Like wise green (ear phone) to green. Leave the blue one. If the computer is an old one, you may need a relatively close inspection.You may see a circle with an arrow going in to represent Mic and a circle with an arrow pointing outward to represent ear phone.

make sure your volume isnt muted...and try both soundcard ports

Try changing the Windows Default Audio devices

1. Go to control Panel
2. Sounds and audio devices
3. The Audio tab
4. Then change the Sound Recording Device to Logitech Headphone INPUT
   

Hopefully this will work

Be sure that your headphone mic plug jack is plugged in to the mic jack (right-most jack) and not the second headphone jack. If so, check your sound setting in Control Panel and make sure the mic is enabled and the volume slider for it is up.

does it have mic on it with cable and headphone mini jack cable then plug it in to eash input one mic one headphone area green