My first kiss....? Guys and girls HELP!.......?

ok so there is this guy i really like and i know he likes me..i get really nervous around him tho and studder and mess up what im saying but he knows that and tells me he thinks it cute and he likes it. Anyway tommorow at 6ish im going to his house for a movie marathon lol (he got a bunch of movies i havent seen) like the hangover and stuff..but my question is what do i do if he trys to kiss me? All we've ever done is hug and i went out with him last week and he said when he got back his brothers were like where did u go did u kiss her..u know things like that..what do i do if he trys..i mean i reallllly like him but im worried ill b bad at it. Im 15 btw hes 17.