Don't know if they even sell them anymore,, but I had a rack on the back of my bike that would hold all sorts of stuff with the aid of a bungee cord or two. The rack was originally designed for a paperroute.
What bike should i get?I want to get a bike so I can bike to school and I need a bike that can support a ton of stuff since I'll be carrying things like an instrument which is a flute.
I would gauge it on the path that you would ride on. For example if you are dealing with hills you may want something with gears to help ease the ride. If its a flat ride all the way through a beach cruiser would be a nice ride and comfortable with room to add attachments for holders. If you want something small and stylish I would suggest any type of BMX stlye bike.
I play flute too. They're not that big or heavy (...unless you have an alto or bass flute, which you should have said). You don't need a special bike. As Soul Fly said, you would probably want to look at what sort of terrain you have to ride on as to what type of bike you get.
Get a giant brand bike heavy duty frame mountain bike u can put on street tires