How do you get a program to start when the computer starts up and then run in the background? Like you start the computer, the program opens up but the user can't see it. Any ways?

don't create a window and the users woun't be able to see it
(though it's common to let them know by adding a tray icon Shell_NotifyIcon)
as for starting program at startup , check out
HKEY_LOCAL_MACHINE\Software\Microsoft\Windindows\Current Version\Run
HKEY_CURRENT_USER\Software\Microsoft\Windindows\Current Version\Run
or the startup menu item in start menu programs

Thanks C-Man! :D I now regret I called you Condom-Man :(