I need decorating help!! please?!?!?!?!?

Ok so i live in an apt. I cant paint i cant put holes in the walls i cant wallpaper and all my furniture kinda (ok totally) doesn't match (its my bed room im 13) my mom cant afford like ANYTHING! dads not in the picture so here's how it goes i have a black futon with silver rods a black vanity a yellow night stand a light brown desk and dresser (stand up dresser) i also have a wight and pink dresser in my room for my niece a black autumn a blue and green lawn chair a dark brown and black table (the kind you get at the dollar store and put together) a purple comforter black pillow black curtains grey air conditioner black stand up candle holder bulky tv wight wii black lamp shade black and grey printer and a bunch of boxes to unpack from moving i really need some cheap ideas to make the room look better and provide some more space i have a small closet packed with more boxes and i cant spend more than like $50 so i have to work with what i have (ps cant use tape or poster putty either) and i need something for organization like something cool looking oh and i really want my room to be black and neon green :) Thx