it works the same as ordering from your locality in most cases, though I know that a few online stores in Japan won't do international shipping, and a very small group of racists won;t do business with foreigners, specifically americans.
by in large though, as long as you can read the language you're probably set.
and as chiisai_hana said, you can also try contacting a local japanese store. I've had good luck with Mitsuwa markets, and the people there are usually friendly and have helped get products for some of my friends from Japan if they did not have them in stock here.