On your Mac, you should have an icon that will start a terminal sesssion (a window with a $ sign for a prompt).
Start a session, and enter:
ssh myuserid@192.168.200.230
enter your password.
You...
A word of warning up front: the following will not help you in any way to "break into" your schools computer (or any other computer, for that matter) and nobody else here will be willing to help you...