Unscrew the old ones at the headstock and put the new ones on where the old ones went and screw them in at the right spot (where you whant them) and do them up tight.
not so easy. first the head light has to come out, the a 5/16 nut inside the head light housing holding on the trim piece that need to come off. one that's off the plastic trim piece on ignition need to be pried off gently, then remove the 2 screws and that cover will come off giving you access to the handle bar mounts
A link to many wiring diagrams for Harley-Davidson vehicles is in related links.
Stock Harley plugs works as good as any.
Inside the tank.
5 or 10 psi
in the manual
install starter motor