Your excitement will be of great use in your endeavor, but you will have a very long journey ahead of you. I'd start with becoming familiar on how to search [php.net. That is the ultimate resource you can find. The next step would be to read up on a few common frameworks, Zend and Symphony come to mind, lastly, check out books from a local library or purchase them online (a good starter book would be [url=http://www.sitepoint.com/books/phpmysql5]PHP & MySQL: Novice to Ninja](http://php.net).
It will take years to become an expert, but if have a natural ability to think logically, you can become a proficient programmer within a few months.
As you run into problems, or need help figuring out where to go next in your PHP endeavor, feel free to post a new thread here.
Best of luck,