Calibrating monitor to printer

The printer and monitor that I am using are way off as far as colors go. I have always heard that it needs to be calibrated by a professional. I was wondering what type of professional that would be.

Has anyone ever attempted to do this themselves??

If somone does attempt to do this and messes it up really bad is there an undo button??

monitor calibrating...

there's a software, but i forgot where i found it
probably on some gamer site...