Laptop screens get very dirty very fast. Here's how you can clean them easily. First buy a bottle of distilled water. Amazon sells them for only a few dollars: Sparkletts Distilled Water - 1 Gallon (3.78 L)
Put a little on a clean monitor cleaning cloth: 3M 9027 High Performance Cloth
and shut off and unplug the monitor. Then you can clean the screen with the wet towel. Your laptop screen should now be clean! Hope I helped!