The SDK makes apps. It made everything in the App Store.
Now you know why people get PAID to program. And why a lot of the applications that people think should be free aren't.
Nothing is ever just drag and drop.
You've gotta know what this means:
Anyway, the SDK documentation has everything you need to know if you've programmed before. If you haven't, then start with a language like Java or even Basic. Then move on to Objective-C.
Programming is more solving problems rather than actual code since the same concepts carry over to all programming languages (unless you're Objective-C).