That much bleeding indicates the dye wasn't set properly into the fabric. The surest way to set dye is to wash it with Retayne. Retayne is available at quilt shops catering to hand dyers, and online from places such as Dharma Trading and ProChem.
Vinegar and salt were traditional methods of setting dyes, but they effective primarily with organic dyes. They often do not work with the chemical dyes used in today's fabrics.
If you don't have time to find Retayne, I would try to return the fabric to Walmart. You can call their customer service first to make sure they will take it back.