Try staring here Xcode User Guide
You mention a lot of things you have done on a computer but no where do you mention programming. While the task you have set for yourself is doable it will not come easy or quickly. You should search out local resources at school or see if there are any after school learning programs where you live. It will be a lot easier if you have someone to guide you especially at the beginning.
Do you know any Objective-C Programming?
A very good start point would be to learn Objective C first.
The following is a very, very, very good book to start your journey in iOS and OS X development: http://www.amazon.com/Programming-Objective-C-5th-Developers-Library/dp/03218872 8X/ref=la_B000APTUFG_1_1?ie=UTF8&qid=1368442862&sr=1-1
Read book on Objective C first, then learn ViewController programming guide that is about iphone user interface, then do some hand on practices such as making a simple calculator app (search in internet, many calculator tutorial). After reading dozens of book, i have no confidence on iphone programming. Only after I 've made a simple calculator, I feel I got it.