Creating a Bugzilla account
All you have to do to create a Bugzilla account is enter your email-address and optionally your real name. You will then receive an email with your password, with which you can login and do anything you want. Just follow this link: get a Bugzilla account.
A "bit" in Bugzilla terms is a setting that allows you to do something. The ones most people doing a lot with Bugzilla should have are the "canconfirm"-bit and the "editbugs"-bit. You probably figured out what they do yourself just by their names but i'll explain them anyway.
This bit, when switched on, allows you to confirm bugs of other people when you have confirmed that the bug they describe is real, moving a bug from UNCONFIRMED to NEW. It also allows you to file your own bugs as NEW, instead of UNCONFIRMED, which saves you time when you know for certain that a bug is real.
The editbugs bit allows you to edit any part of a bugreport even if you haven't filed the bug yourself. You can change the title, keywords, component etc. to what you think is best. Having this bit means you can automatically also confirm bugs.
How to get these "bits"?
When you think you have earned the right to have either of these bits switched on for you, contact us. Do not hesitate to mail the mailing-list or ask on our IRC channel. If you mail the mailing-list, give us the numbers of a few bugs you filed or bugs you commented on, so we can check if we think you've earned it too.