Depends on what pattern you want. You can spiral, bullseye, crumple... you want to create folds in the fabric so some parts take dye and some don't. With bleach you just need to be careful not to leave it on too long or it will burn holes. If you want to dye it make sure to use a cold water dye (not RIT) with a fixer. Here's one I did a little bit ago:
And a bleach dye my friend did: