If you don't buy PFD fabric, you will need to prepare the fabric your self.
You want to wash it well, and do NOT use any kind of fabric softener. Rinse it several times too, anything left in the fabric can keep the dye from taking very well.
Read all of the directions on the dye container. I have used Rit dye, but the others seem to do a better job for some techniques :D:D:D