If you don't want to spend money then just google for php tutorials.
But I would recommend getting a good php book, I'm sure there are many many out there, if you go through a full book, you will know enough to do a lot, and when you are working on your project you will go learning on the fly, depending on what you need to do.
You will also need to learn about databases if you don't know about that yet, mySql for example or any other db platform.