It depends on if you want registered Fullblood, purebred to percentage.
You would want to join an association, for the kind of goat you are wanting to register, read the rules for registration ect.
If you have quite a few to register, it is wise to join as a member, so, it is cheaper per goat.
If you are only registering a couple of goats, you don't have to become a member, I know this about ABGA.
Choose a herd prefix, so when you tattoo a goat, you have your mark as breeder in the ear to match registration papers.
What breed are you looking into?
First, look up a website to an association and check out rules.