The log-in mechanism used in these webpages is just a simple way of keeping track of developers who work in projects hosted in this site. When a developer logs in, she/he is conducted to a personal page that lists the projects she/he is collaborating with and any pending tasks that she/he might have.
If you are not a developer, you don't need to log in since it will make no difference. If you want to register a project of your own to be hosted in this site, you must first log in, because every project must have at least one administrator and we need to know your user name to make you the administrator of the project.
In order to log in, you must be registered (using "New User" in the menu) and give the user name and password selected during your registration. Please keep in mind that this user name will be used also to give you access to the CVS repositories and upload areas of the projects you are involved with, but the web password will not grant you access to those services. To get access to those services you must send a SSH public key for the machine(s) you use (for further details, after you log in follow the link to the "Account Maintenance" page and see the section "Shell Account Information").