How do you know if you fancy a boy?

You will definetly know if someone "fancies" you. They will be around you a lot and make an effort to be around where you are at social gatherings. If they have enough courage they will ask for your number or give you thiers. If you have enough courage ask them or tell them where you will be next be next weekend and offer them to come. Everybody has a gut instinct and you could also ask friends too. they're watching and they know more than you think!