If you do i would appreciate it if some told me how to jailbreak

Jailbreak - in what sense? Do you mean "Is there any way to upload / download programs from a different server?"

How do you write your own operating system

You gotta be good at Basic, then you can just use abstraction to create a bunch of functions, you could store the entire file system into a single .txt file, and create a GUI that can run multiple windows at once. It really isn't that diffficult In fact there's some great ones that are already made!

Its easy to jailbreak the iphone sim :)