I’m often asked how I taught myself to code (the hard way ;-))
My top 2 favorite resources for learning PHP (and where I developed most of my own PHP coding skills) are:
Especially helpful for understanding everything you need to know about working with arrays
Simple step-by-step tutorials, starting with how to actually install PHP on your computer.
I’ve also found John Post’s site helpful, especially for it’s repository of PHP functions and it’s PHP Sandbox, which allows you to test your PHP code.