Navigating the DOM in jQuery is incredibly simple and thats to phpQuery you can do the same in php. Below are some examples of how it's used, the key change bing that instead of $() you use pq(), and instead of a . you used ->. Theres alot more details information at the link if your interested. Post questions/comments here or there.

You can get the phpquery files, and well as read the manual at the google code page here: http://code.google.com/p/phpquery/