i think the best way to learn to roll is buy a pack of zig zags.
sit down with a sack and roll, roll, roll, your little heart out.
till you get it just right. its good to have someone show you how they do it but i think its necesary to develop your own style, when i first started rolling i was trying to hard to do exactly what the person who taught me did and i couldnt do it, just let your fingers go where they feel like; joint rolling cannot be forced.