If you had an account on the previous Bugzilla database, you need to enter your email address as the user name (just as in Bugzilla) and request a new password, because the old passwords were not imported.
All users have read access to all entries. All registered users can create new bugs and add comments and attachments to existing bugs. Only users with "developer" permissions can edit all aspects of bugs. If you think you should have developer privileges too, send me an email.