Well, there are two ways to become better at php
a) Read a lot of php. While this is not a bad idea in itself, there are horrid things out there that a novice really should not learn from. Actually, most of the code I have seen so far has been pretty bad.
b) Write. A lot. After the first 30000 lines, you'll discover that 3/4 of what you're doing is just repetition. So refactor mercilessly.
Read the php manual. At least the sections "Language Reference", 'variables', 'string functions', 'arrray functions'. (typing out of my mind. check for names similar to those).
Hop over to the original wiki on C2.com. Read there till your eyes water and your finger hurts from following the links.
So long,
Tyberius Prime