Take a tap water sample to your nearest hot tub/spa business. They'll test it right there and tell you exactly what you need to get started. Make sure you get plenty of test strips.

From there, it's really not that much maintenance. Just test it every few days and add the appropriate chemicals if needed. It's usually not much. We had one, and it was great to have in the beginning, especially in the winter time, but after a while we just didn't use it much and eventually got rid of it.