The PHP project uses CVS for tracking it's code. For using php.net's CVS server please check http://php.net/anoncvs.php For getting write access on a repository you can request an account on http://php.net/cvs-php.php - before doing that please check with your mentor to define what kind of access you need for your specific project.
If you are using anything other than CVS then make sure its public and noted on your project page.
For code written in the C programming language please mind our general standards: http://php.net/reST/php-src/CODING_STANDARDS Projects written in PHP should follow the PEAR Coding Standards: http://pear.php.net/manual/en/standards.php And again: Your specific project might have other standards, please check with your mentor.
At a minimum status updates should be sent every 2 weeks, these should be sent to the appropriate mailing list and cc'd to firstname.lastname@example.org, your mentor may ask for more regular updates.
You can find a template for your report here
Let your mentor know and ideally document this on the wiki page, especially if you're going to miss a status update. We'd rather know why you weren't working than having to make assumptions.