You pretty much make it the same way you would tea. You can use a tea bag(I use one when I make a chamomile rinse), a tea ball(I bought one from a tea store in the mall), or a coffee maker(I use a coffee filter but add the herbs in instead of the coffee). I think using a coffee maker is the easiest way and the herbs never mix in with the water. You just wait for the tea to be cool to the touch obviously before you use it.
You just pour the rinse over your head. If you have dry hair you can use it after washing your hair where you massage the rinse into your hair and scalp and then condition it. Or you can use it as a final rinse if you have oily hair.