This is a quite lengthy process.... first you do paint the whole floor white. Then you need to basically draw the checkerboard pattern on the floor with a pencil or fine tipped permanent marker. Then mask off each square that you don't want painted, and then paint the rest of the squares. It took me about 2 days to do the later part of the project in my 2 car garage
Use string stretched out across the floor, draw with chalk!
Firstly paint it all white
Then get some card and cut it into a square and use that as a guide
Then get some card and cut it into a square and use that as a guide