If you want to use Bugzilla, first you need to create an account. Consult with the administrator responsible for your installation of Bugzilla for the URL you should use to access it. If you're test-driving Bugzilla, use this URL: https://landfill.bugzilla.org/bugzilla-2.20-branch/.
Click the "Open a new Bugzilla account" link, enter your email address and, optionally, your name in the spaces provided, then click "Create Account" .
Within moments, you should receive an email to the address you provided, which contains your login name (generally the same as the email address), and a password. This password is randomly generated, but can be changed to something more memorable.
Click the "Log In" link in the footer at the bottom of the page in your browser, enter your email address and password into the spaces provided, and click "Login".