How to act at a party/small get together?

okay so im not going to lie ive drank before and smoked but I never went to a party with a bunch of friends. I just am worried I'll act weird or it'll be akward. so once everyones like drunk im imagining it'll be fun lol but i just am worried that I'll look dumb and not know what im doing lol please help they arent super close friends either