Once that's done, you'll be asked to either enter an existing Apple ID or create a new one. Your Apple ID is an account that you'll use for a lot of things, from buying at iTunes to using iCloud to making Genius Bar support appointments, and more. If you have an existing Apple ID that you've used with a previous Apple product or to buy an iTunes, log in with it here.
If not, you'll need to create one. Tap the button to create a new Apple ID and follow the onscreen prompts. You'll need to enter information like your birthday, name, and email address to create your account.