I am starting to make apps for the iOS platform and OS X platform and I would like to make a school system with an attendance register, homework planner, mark book, behavioural reports and I was just wondering how to do this in xCode
Double time that.Well, that's an awfully vague question.
Just create some classes and some UI and build it and you are done.
Hey, you forgot step 3: profit!
To the OP: if you don't know anything about programming yet, you're in for a long road. It's likely to take you a year or two to get to the stage where you could attempt an app of that scope. Your first step should probably be to buy a book: you could try this one, for example, but there's plenty of good ones.
Whether or not you know anything about programming, you should read this article about how to ask questions on web forums. Read every word of that article, then go through the checklist at the end. Then come back and post about your problem in more concrete terms. If after reading that you still can't ask a more specific question, then you need to buy a book and work through it.
Amorya
Yes I do know a lot about programming but how can I use MySQL database and design the UI for this app