You are welcome to register on the forum to become a member.  After your registration is confirmed you will receive an email confirming this, but you won't be able to log into the gallery as they are two independent systems.  Administration will review your registration, ensure that it is correct and if so, will create an account for you on the gallery then confirm this by another confirmation email which will contain log in details and instructions to follow.

Please don't just try and log in, you have to await notification of your account activation, otherwise you will waste your time and the administrators as well.