Am I going to lose him over some new girl, guys Please help too and girls?

Okay, so I'm in 9th grade know and were getting new boys & girls in my class, so my question is I like this guy but idk if I should tell him cause last time I told him I did not like him :( but now seams to me that he is going to like one of the new girls but I know he likes me, what should I do!? Please help me thanks