this is the way we use to do it. We got plain white shirts and tied rubber bands around the parts we wanted dyed. we put the paint in some bowels and dipped the shirt (parts tied by the rubber bands) in the different bowels
I could explain it but this website has the best explanation I've ever read, and some really creative ideas too :) http://funadvice.com/r/bgcj8njte4o
Yuu Can Buy A Tie Die Kit From The Store!