My best recommendation would be to find a book on the subject that walks you through, step by step, and is easy to read. I just said this elsewhere earlier, but I really like the Sitepoint books for exactly this reason. Then find a good PHP reference (O'Reily or something similary) and keep sites like w3schools.com bookmarked for syntax questions and such. And join a PHP developer forum where you can ask questions.

Of course, you'll never do any of the above if you don't have a good project to keep you engaged in the subject. But it sounds like you do.

--Josh