Thanks so much,
There are so many different ways that this task can be handled, depending upon the requirements of the application, that I don't think you are going to find a black-box solution you can succesfully drop into your program.
The good news is that tracking users is not a very complicated task, so it should not require many tables or a lot of SQL coding, depending upon how complex you want the security and user-rights to be.
And since you are only 13, you have many years to figure out what is going to work best for you.
If you decide to take on this task and have specific questions, then please post them here and we will try to help you out.
....now go finish your homework!
If it's not practically useful, then it's practically useless.