Contribute to PHP

Deal all phpiers, It took me a while before I hit the send key. I have been a php developer for some time and I got certified beginning of this year. I have always wanted to start contributing to php and zend framework, but I am unable to find the right docs, examples, and the "how". I know it might be a simple task, but I appreciate your support as I really want to contribute some good stuff to the php community. Appreciate if someone can share a reported bug, how he traced its location and how he got it fixed. Many thanks, Ziad