Steps for changing desktop icon size.
1. Right Click Desktop + Choose "Properties"
2. In the Properties Window click on the "Appearance Tab" at the top.
3. In the Appearance Window click on the button called "Advanced"
4. In the Advanced Appearance Window choose "Item:" from the drop down list and choose "Icon" and you can choose desired Icon size. By default many users will see 32 x 32 pixels but this can be changed to whatever you want.