How do I record a moth that is not listed as in my area?

IRecord uses the UK species inventory, so has a fairly uptodate list of UK moths. So it doesn’t matter if a species hasn’t been recorded in your area before, you still just use the casual record or list record options, choose the species and add the location as you would with common species. If you are talking about something new to Britain then that would need the ID checking so it could be added to the British list.