If you are not knowledgable in PHP you may have some difficulty finding a script that follows best practices and (especially) is CURRENT. Avoid scripts that still use magic quotes, the mysql db interface (look for ones with PDO instead), and ones not using modern encryption techniques for the password field. This alone could be a big problem for you.
If you are thinking about learning how to code, then this single exercise could be the start of your learning experiences. Read, read and read some more and learn how to code and how to write proper scripts.