Just like the title suggests, I would like to know if I can color points based on if their normal is facing a positive y value. Not sure how to write that in vex. So if its facing up its white if not then black. Thanks.

In it's simplest form you could try this inside a point wrangle.

Enivob
v@Cd = {1,1,1};
if (@N.y<0){v@Cd={0,0,0};}

This works perfectly thank you!