How to paint walls with a roller To paint a wall with a roller first you need to cut in the wall with a paint brush along the top and the sides of the wall. Take your roller and put it in the paint pan to put paint on the roller. Load it up with paint just short of it's dripping point. Then start over to the left and roll down diagonally to the bottom of the wall. Roll straight up to the top of the wall and then straight down to the bottom of the wall. Always roll all the way up to the top of the wall and then all the way down to the bottom of the wall. When you need more paint just repeat this process.