You've literally just asked how to do your entire NEA. I'm in year 12 and our teacher showed us your NEA as it's much easier than the one for our year- you should have no trouble doing it if you have any programming ability (which you need for the exam anyway). If you can't do it you need to ask the teacher to teach you not ask for answers here.
And asking here is dangerous anyway. Our NEA last year for cancelled for people asking for help online and although they've loosened the rules this year, this is still plagerism if you copy someone from a forum which could get you disqualified from the NEA, Computer Science GCSE as a whole or even your entire GCSEs.
So be careful and get taught properly instead of asking for answers online.