Normal colour code is;
Yellow =Alternator stator wires
Black = NEGATIVE - (put your fuse in here)
Red = POSITIVE + normally goes to frame

If the unit has a built in capacitor you cannot disconnect just the capacitor.
It will be in the circuit all the time. You won't notice it. (Until you want to start the bike with a flat battery)
Just connect the unit up and use it.

The above comments are related to fitting a separate capacitor, don't worry about them.