My 13th Birthday

Ok im haing my 13th birthday in may but idk what to do
I was planning on inviting like 100 ppl boys and girls, i sorta want it to be outdoors at a park with a dj but then i want ppl to dress up in like nice clothes but then i feel it would be lame to dress up on a hot night. I was planning on having a dj and all but then i feel they might get bored so idk what else to do. Then again idk what we should eat becuz pizzas are to expensive. So should they dress up or just where whatever. What kinda food and what else should we do besides dance??