To set your resolution to 800 X 600:

Windows 3.x
1.Double Click on Main icon
2.Double Click on SetRes
3.Then set the resolution to 800 x 600

Windows 95/98/NT/2000/XP
1.Click Start, and go to settings  
2. Click on Control Panel                       
3. Double Click on Display
4. Click on Settings
5. Move the Slider to 800 X 600
6. Click Apply   
7. Click OK

 MAC
1.Click the Apple Menu
2.Scroll to Control Panel
3.Click on Monitor
4.Click the Options Button
5.Set the resolution to 800 x 600
6.Click OK