You basically create the app in iTunesConnect and then you get its Apple ID, which consists of a number. You will see this full ID once you have completed registering your app.
So go to iTunesConnect, select Manage Your Apps and then Add your app using the button at the top or select an existing app. Under App Information there is the apple ID given.
You can then later upload your app to iTunesConnect.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…