Watch a YouTube on a Bimini twist. Seriously. It's pretty easy. Tie a Bimini on the end of the backing. If he has a fly line already and it was made in the last 20 years, attach the reel end of the fly line line (running line) to backing using Bimini twist's loop. The fly line will have a welded loop on it. Spool up the fly line. At the fish/water end of the fly line there will be another welded loop. Purchase or make a leader specific to your rod and line setup and fishing application. Connect leader to fly line using loop to loop. At the fly, I prefer a nonslip mono loop for most applications.
I live in BCS, PM me or post contact info if you need help with what I'm describing.