i wish create a php page using a browser in fullscreen where students cant open any other program or browser that they may use to cheat. since iam making an exam php program where an alt+tab may be used to run some windows programs.
Ah, OK, I have seen such things. You probably need to get a hold of the right API and turn it into a web application instead of a web page. I am assuming the code is in java, but I am not a developer. I have seen such things as I work in academia, but off the top of my head I can't tell you.
You'll have to disable task manager as well, somehow...that'll probably be a bit more difficult.
edit: Actually now that I think about it there are quite a few commands that will either open a new window or display the taskbar. Maybe there's a way to lock keyboard shortcuts in general?