First, go to the Start Menu.

Second, a variety of options will show up. Click on Settings and a few more options should show up. Click on the one that says Control Panel.

The Control Panel Window should pop up, showing you a few shortcuts.

Click on the Display Shortcut

The Display window should then pop up.

You don't need to pay attention to anything except the little box that says Screen Resolution. The numbers at the bottom of the arrow are the number of pixels your screen is (lenth x height). Most school computers have the default at 1024 by 768 pixels, which is what the numbers are set at now. If they are set otherwise, you just need to move the arrow by clicking and dragging it until the appropriate numbers show up.

Once you have a satisfactory setting, just click the Apply button at the bottom of the Display Properties Window and you're done.