apple developer program

Well, if you're wanting apps to be available on the app store then you sign up for the program and pay $99/year. You get access to the developer forums in Apple's site and the betas plus the latest xcode (the environment you write iOS apps in). As for whether it's easy... Not possible to say without knowing your background.

If you're just starting out in programming and will be using objective c then I'd say it's not easy to do anything useful. If you're wanting to use a code generator like Flash's export to iOS apps then it's probably as easy as your familiarity with Flash. But like with any development project, the more important or useful an app is the longer and more difficult it is to take it from idea to completion. To paraphrase a famous quote: there's no Santa Claus in software development.