Preparation!?

[Shex]

Thanks a lot already, I'll especially take a look at OOP
I already had a short course on OOP with blueJ and javascript, but that's years ago and I really didn't understand most things, I hope that will be better now :)

Another aspect I really have problems with: How do I learn to make a secure page? I read about sql injections and exploits, is there a way to check those things or any information on how to code secure stuff?
I'm really concerned about that but haven't found useful sources yet