To check how many copies/how much money is left on your student account for copies, you will need to log in to a computer in one of the labs using your student id/password, click on the tiny arrow in the bottom, righthand corner of the screen, and look for the icon that indicates student account information.
If you need assistance finding the on-screen arrow, come to the library; and one of the librarians will show you where to look on-screen.