How do I connect a hooter (horn)from beginning to end please.

Using a multimeter set on the direct current icon, use one probe on the live side of the hooter itself and the other on the negative point of battery. With ignition on, press the hooter button and check for reading, it should be that of battery, if less then you have a short/draw/open line on that circuit.
From there check for continuity on hooter itself.
From there, check for continuity from hooter to frame and from hooter to switch and to relay (if applicable) and to battery.
Hope this is clear enough.

Place a test lamp (12v bulb) across the horn contacts. Press the horn.
If it lights the horn is faulty, if nothing, probably a broken wire/connector.

12.3 volts is a bit low - maybe your battery isn't fully charged or is past it's best.

You should find the wiring diagram here...

http://usa.jeremyjudkins.com/goldwing-wiring-diagram.pdf

i don't know. check the wire's connection on the horn.
use volt meter to see if voltage is reaching horn when
pushed on at steering wheel. if not, check fuse.
use meter to check 'continuity' between horn metal and cars frame. if not., ground horn to bare clean metal.

Sounds like worn contact points beneath your air bag OR lose horn connecting plate.
If you are a or know a handy man that can take apart your steering wheel without the airbag going off (not always advised) then you will then be able to make the connections more solid.

Found you this video...

By hooter I assume you mean the horn? On Mercedes these are controlled by the AAM or all activity module. That's just a computer module that controls the human interactions amongst other things with the car. Airbags, horns, wipers and all sorts of weird stuff is not directly connected to the switches you press. So in your case the problem may be in the wiring or connector but can also be the aam.UnfoUnfortunately you will need to go get it connected to some version of the Mercedes diagnostic software (star system). This will read a code and tell whatever the issue is. It is not the same diagnostic that the normal mechanic can read and usually only found at Mercedes or shops that deal with euro vehicles. This is a pain and will cost but it might be as simple as the code nearing to be cleared. Then the aam will recognise it is connected to two working horns again and allow them to be activated. Before you do that check your wiring and connectors, look for corrosion and or bent broken pins or wires. I would have to look up the fuse or relay for the horn to tell you but those need to be looked at as well. This is the same stuff a mechanics will do but you are cheaper so it's worth doing.

I assume you mean the horn. This sounds like a wiring problem. You may have a wire that has lost the insulation, either by rubbing or by rodents. When you go around a corner, the wire shorts to either another wire or come grounded metal which sets off the horn.

Go to www.vaglinks.com. You can download "Golf,Jetta_MKII_serviceManual.pdf". It has got all the d=info you need.

most likely cause is the horn itself ,check for a feed to the horn before you go any further but some vehicles have a permant feed and the earth is the switch contact connection .if two wires then it could be the latter ? you must check it with a multimeter to determine the fault

HORN?...FUSE, RELAY, BREAKER,WIRING,GROUND....OR YOU NEED A NEW HORN!!!!
CONNECT FUSED JUMPER TO HORN W/12 VOLTS IF HORN (HOOTER) SOUNDS...CHECK PREVIOUS ** MAKE SURE HORN IS GROUNDED FIRMLY