brushes

ok,i know how to make brushes from pictures and was wondering if this is the same way to make brushes from words?  and what is the best size to make them? also, where do the brushes that i make go to so that i can get them to make a brush zip? i can do it ok with pics but not the words and stuff. sorry if this has been said before but i cant find it in toots and i would love to have a go at making my own word brushes. thanks. :-)