Just kiss him..

If ur nervous to kiss for the first time... Just do it. You,ll have ur first kiss. And it will be over with. If you like him a lot, and he likes u, he would want u to kiss him. If you guys have been dating for 3 weeks... And no kiss.... Kiss him.. And then that will start making u both feel comfortable, and most likley, you guys will eventually kiss more. Good luck! :)