How do I claim my character?

In the game, at your character's first login, Homerealm shows Claim your character. You can also find it on Homerealm's page in the game's Options (AddOns), or type /homerealm claim.

Press it once: the game reloads, and your browser opens on Battle.net's own sign-in, which confirms the character is yours. Homerealm never sees your password. Every character on that Battle.net account then joins your account.