The forums hosted at Mathforge use the same login information. So if you already have an account on one of the other forums, please go back to the sign-in page, sign in with your existing account, and follow the instructions that will then be shown.
To create a new account, please fill in the form. It is strongly recommended that you use your real name (spaces are allowed). You will then be sent an email to confirm that the email address that you gave is active. Please click on the link in that email to confirm your account. Once you have done that, your Mathforge account will be active and will be automatically linked to this forum.
Once you are signed in, you can add OpenIDs to your account to make it easier to log in. To do this, go to the "Account" tab and select "Manage OpenIDs" from the menu in the side panel"