Where can I buy tie-dye?

You can buy the dye at craft stores such as Michaels, JOANNs, Hobby Lobby, and online in places such as amazon. You can buy individual colors or buy the kits where all you have to do is add water! Popular brands of dye include Rit and Tulip.  You can even buy tie-dye on websites such as Amazon where there is most likely a wider variety than in a store, however if there is a brand that you haven’t heard of, I suggest you read the reviews or try to find a tutorial on Youtube where there is a demonstration with the dye of said brand.

Can I wash multiple dyed fabrics at once in my washing machine?

You should only wash multiple dyed fabrics together if they are dyed with the same color scheme. If the fabrics are all different colors, they should be washed separately to avoid any chances of becoming muddy or the colors becoming dull as they bleed out in the water of the washing machine