Welcome to everyone who is registering for the forums.
Currently, your game accounts are NOT linked here to the forum by default. Therefore, you’re going to have to make your account here. (The details can be the same as your game account. However, if you change your game account password, this will NOT change your forum account password nor vice versa.)
If you’re new to City of Heroes: Rebirth, visit this thread here for a guide on how to install and play on City of Heroes: Rebirth.