I assume you have previously created a Apple ID? It is usually your @icloud.com email address unless you created the ID with a custom email address. But the ID is a email address.
As you try to guess what it was I would do it with a computer at http://www.icloud.com so you don't have to keep typing on phone. Once you figure it out you can then type it on your phone.
Once you figure out what your ID is but you still can't remember your password ***** to http://iforgot.apple.com you can also go here for help finding your Apple ID by your name and email address. Let me know if you have any follow up questions.