Clean the wall using a mild cleaner and allow the wall to dry thoroughly. Fill any nail holes using spackling compound.
Lay a drop cloth over your floor where the floor meets the wall, and tape the drop cloth along the edge of the wall using painter's tape. This tape can be removed without peeling off existing paint or leaving a sticky residue behind.
Fill a paint tray with blackboard paint, which is available at paint supply and craft stores.
Coat a 2 inch flat paintbrush with blackboard paint, and apply a strip of the paint along the top edge, bottom edge and corners of the wall.
Coat a paint roller with blackboard paint, then apply the paint over the surface of the wall using the coated roller. Cover the wall with an even layer of blackboard paint.
Allow the paint to air dry for 8 hours, then apply two more layers of blackboard paint using the same methods as before. Allow the paint to dry for 8 hours in between the layers.
Remove the paint tape and drop cloths before use.