To get access to resources of the project like this wiki or the Forum, you will need an account. This account is used to get in touch and traceback changes on the documentation.
It is not very comfording to have several accounts just for one project, so there is only one single account useable for the most important services: the forum and the wiki.
Go to the registration form: http://forum.ipfire.org/index.php?action=register
After confirmation of your email address, you are ready to start.
To get your hands on development ressources, there is a developer account required.