The BEFORE picture…
I searched and searched and could not find a better photo than this of my niche before the change. I believe this was taken the day we were having our floors replaced. It’s not a direct photo but you can see how plain the wall is.
Tape the edges of the area you will be painting. Then paint the entire area white.
Measure and mark the width and height of the wall, then, using a level, draw a straight line on those marks. Where the lines intersect is the center of the wall.
Measure and mark 1″ on either side of the intersecting point on both the horizontal and vertical lines.
Use a level to carry those outside marks to the ceiling, floor, left and right edges.
Your markings should look like the following pictures. The space between the lines is 2″.