I want to manually edit some entries in my database. How?

There is no facility in Bugzilla itself to do this. It's also generally not a smart thing to do if you don't know exactly what you're doing. However, if you understand SQL you can use the mysqladmin utility to manually insert, delete, and modify table information. Personally, I use "phpMyAdmin". You have to compile a PHP module with MySQL support to make it work, but it's very clean and easy to use.