Well, it is actually quite simple. I have been asked this question every time I had an interview.
Tell them, in your own words, in a conversational tone, where you grew up, you can mention a hobby, especially if it is somehow connected to the work you do, maybe you have a little anecdote about something that happened to you, what your aspiration for your life are, preferably in connection with work, keep it light and conversational. It is not difficult, do not worry too much about it.

Oh, and I ALWAYS got the job I applied for. :)