User accounts on virtualbox.org
If you are not yet logged into virtualbox.org, you will see a link on the top right. Follow the "Login" link to sign up an Oracle Web account. Once you have successfully registered an account, you can login. You can now create new tickets (bug reports) in the bugtracker and post new comments in existing tickets.
You do not need a user account for anything else. You can read all tickets and forums without being logged in.