tHERE WILL NEVER BE "INSTRUCTIONS" FOR A JELLY ROLL! A jelly roll is simply strips of fabric already cut for you. YOU use them as you decide.
As an example, suppose you piecing a quilt that calls for stiprs 2 1/2 X 6. All you'd have to do is cut a 6" piece from one of the strips in your jelly roll. Or suppose you needed 2 1/2" squares. The jelly roll (normally) is already cut to 2 1/2" strips, so you'd just cut 2 1/2 piece to get 2 1/2" squares! There are "Jelly Roll' books out there, specifically with a slant, obviously, to using the strips in your jelly roll to create beautiful things.
Very simply put, look at all pre-packaged cut fabric bundles as simply fabric where some of the work of cutting has already been done for you. I hope this helps! Happy quilting!