I'm in middle school and I want to become popular I just don't know what to talk about talking topics please

Is middle school 14?
Ok things to talk about movies, TV shows, music, sports, books, how much you hate a certain teacher, fashion, the opposite sex, how much you hate x subject, what you want to be when you grow up, internet sites, jokes. That's pretty much what I talked about at school.

Right starting a conversation - start with a compliment. You have to be sincere though or it won't work.

Wow I love you earrings - where did you get them from?
That's a really nice drawing- do you do art? Can you do me one?

The there is sharing
Does anyone want a malteaser/ smartie/ crisp?

Also good conversation starters are just the random question
Do you think butterflies can think?
If you had a ferret what would you call it? I think I'd call mine George.

And lastly topical issues
Don't you think it's terrible that x happened to y?
I can't believe they are making us wear these stupid swimming caps, I look like an alien.

Just smile and be yourself. And never worry about making a fool of yourself - if you show you don't take yourself too seriously and can laugh at yourself you'll be very likable. Also if you don't worry about what people think about you then you will appear more confident and people will like you more.