Weight Training?

Hey I'm 16, I weight around 130lb, and I'm 5'8''. My workouts consists of,

Pushups in 5 minutes: 100

Pullsups: 15 if I push myself, but mostly 12 with good form

Dips: 12

Squats: I don't do leg day but I Need to. My knees have that poping/cracking sound when I squat.

I dont want to do cardio, soI heard adding weights would make it harder for my muscles and should help me get more gains.

What food groups should I be eating? What meals do you all eat per day that help you?