Hello @toadisme sorry to hear you are having trouble registering for MYEE online. Try another device or browser if you can, or logging out then clearing the cookies/history of your current browser then trying again.
If none of the above work please call customer service on 150 from your EE phone or 07953 966 250 from any other (lines open at 8am) who can register the number for you. If you are a personal pay monthly customer on an EE plan you can also browse the pages on http://ee.co.uk and click the popup box when available to speak to live chat. 🙂