Reducing screen size

I am wondering how to reduce the screen size less than 800x600, like a folder size.



I just watched Youtube video that adjusts screen size much smaller than 800x600.



My laptop cooler makes loud noise when I run 4 bots.. I need some help.. thanks







the video linked (1:10 ~ 1:30 secs)



http://ift.tt/Yvq2OA

Reducing screen size