CMD commands

It's basic to say the least in comparison to some hacks people produce, but a friend of mine knew how to get cmd at school so we played around with it but nothing worked as we have the normal accounts and a lot needs admin control.

How can I get passwords of specific accounts (Simple and admin) and shutdown specific computers? Also, I made a very simple .bat file that can crash your pc with flooding of opening cmd and tried to put it on the P:/ (Public) drive at school but only I could open it (That's useful eh). How can I change that?
Is there anything else interesting I might want to play around with too? We really don't care about being belted by the technicians and the principal... we just want to mess up some other arsehole's computer at school.

Thanks for reading

There's a program I use its called net control 2 you could draw on peoples computer etc.

That friend being me <3
we really need help :3
please help