Start at a hello world and work your way up. The best way is to just purchase a book on the subject.
This one looks pretty basic http://www.amazon.co.uk/Beginning-iPhone-Development-Exploring-SDK/dp/1430224592/ref=sr_1_1?ie=UTF8&s=books&qid=1281003097&sr=8-1
You really need a good book, I recommend Beginning iPhone 3 Development by Apress.
In general, I'm wary of Games Programming books. I find it better to learn from a normal programming book, and apply what you learn into games. Then you can use the Game Programming book as more of a reference.
I use this:
But I learned iOS from this:
The best place to start learning iPhone/iPad programming in general is to read this book:
And more specific to your question, yes, apps are allowed to access the iPod music library in the phone, through the MPMediaQuery class and its brethren: