How to repair a headlight bad ground wire on my 95 Subaru Legacy?

I have a 95 Subaru Legacy Lsi wagon and one headlight is dimmer than the other. It seems to be a bad ground. Looking to repair it myself.......I've put in new headlights before but never fixed the ground wire. Can any specialist out there give some advice or a walk thru on how to fix it myself......really dont feel like paying the dealer or a mechanic shop.