Okay so I want to go to a basketball camp and I went there almost 4 years ago but I didn't know anyone there so I was all by myself. So this year I am going and I don't want to be all by myself I want to make some friends there so what do I do

Talk to people. If it's a basketball camp, you have at least one thing in common with everyone there-you all play basketball. So you can use that to help break the ice.
"what's your favorite team?" "you guys wanna play?" don't be discouraged if you don't have anyone to hang out with right away. Just keep talking to people.