be sure to read the packages when you get to Joannes---they offer more than one kind----some are washable---some are not- some need to be dry cleaned---some are for wallhangings--items that do not get laundered.
once you choose the one that fits your needs---follow the instructions---each has it's own specific (needs) heatset, rinse, cure....
also, make sure you are using good (expensive) permenent ink in your printer---the inexpensive refills will rinse right out---they are actually made to wash out.