Charlie gave a nice, detailed answer (just remember to introduce yourself as “Naomi”, not “Charlie”).
This is really not a trick question — the other person just wants to know the name that you would like them to call you. They may pop this question if you’ve given them a name that they find too difficult to pronounce or remember, so have a suitable name in mind, be prepared to spell it (in a language your conversation partner understands) if necessary (native speakers do this all the time, as names can be spelled in many different ways). If this came up in one of your online English lessons, your teacher should have helped clear up your confusion then and there.