Rather than go into some complicated description of how to tie these knots (they're not hard to tie, just hard to describe), I thought it would be better to show them to you. Below is a page from an old booklet that Scientific Anglers used to include with their fly lines back in the early 1980's. It shows, & describes better than I could, how to tie these knots. I have found it to be an excellent reference.
So the next time you have all the line &/or backing off your fly reel - or when you add a new reel to your arsenal, be sure to attach the backing & fly line correctly. This way they will lay flat in the reel spool & won't come apart when your trying to land that big one!!