Alright, this part is easy. As an app developer you need to enrol in the iOS Developer Program to get your App Developer Account with Apple, specifically with iOS. This is how you do that:
1) Click the “Enrol Now” button.
2) Then scroll down to the bottom and click “Continue”.
3) Now I’m going to need to make you think. Here you are asked to Sign in with an existing Apple ID (every iPhone has an Apple ID) or create a new one. The latter is generally for businesses/partnerships or if you are involved with certain other Apple services. Pick whichever one suits you best and click “Continue”.