In this video tutorial, viewers learn how to tie a fly fishing line to the backing. Users will need a nail knot tool. Put the backing into the tool, leaving about 6 inches sticking out. The wrap the line around the tool 5 times, pushing the loops together. Take the end of the line and run it through the groove of the tool. Put the fly line through the other end about 2-3 inches. Then hold the loops in your hand, remove the tool and pull on the backing to tie it. This video will benefit those viewers who enjoy fishing and would like to learn how to tie a fly fishing line to the backing.