Use only braided nylon or dacron line for fly-line backing. Never use nylon monofilament for backing. Monofilament stretches too much to be used for backing.

Free the end of the backing line from its spool and pull off about six feet. Pass the backing line down through the rod's large stripper guide (the one closest to the reel) on the rod's butt section. Now pass the backing around the reel's spool, entering at the line guard opening (forward and front of reel), passing it around the spool and back out the line guard opening.

Take care not to allow it to pass between any of the reel's frame posts.

Tie an Arbor Knot knot with the backing tag end and incoming line, and slip it down tight against the spool arbor (center post). Trim off the excess tag end after the knot has been slipped down tight on the spool arbor.

WINDING BACKING ONTO THE SPOOL
Place a pencil, stick, or dowel through the hole in the backing spool. Have another person hold the spool as you wind the backing onto the reel. Be sure the backing unwinds slowly, under light tension.

Holding the rod's butt section by its handle with one hand, begin winding the backing onto the reel with your other hand. Keep the backing spooling onto the reel evenly by using one of your rod-hand fingers to move the backing back and forth across the spool. Keep reeling under modest tension until the needed amount of backing is on the reel. Be sure to stop reeling before the end of the backing comes through the rod butt's stripper guide.

The backing and fly line together should fill the spool to within a half inch of the cross frame of the fly reel. This space compensates for less careful line spooling when you are fishing.