2. Register Your Apple ID
You will need an Apple ID to download Xcode, access iOS SDK documentation, and other technical resources. Most importantly, it will allow you to deploy your app to a real iPhone/iPad for testing.
If you have downloaded an app from the App Store, it is quite sure that you already own an Apple ID. In case you haven't created your Apple ID before, you have to get one. Simply go to Apple's website (https://appleid.apple.com/account) and follow the procedures for registration.