I want to do my room checkerboard, purple & black. But I need ideas ?

How big is the room? Remember that dark colors will make a room seem much smaller. You need to paint the wall purple first. Allow sufficient time for the paint to dry fully. Ideally at least 24 hours. Measure the wall height and length and divide equally. Mark the wall at each end with a light pencil. You may need to put a couple of interim pencil marks to make sure you get a straight line. Use a low tack masking tape to mark out the checker board. you can then paint your black squares. If you decide to use purple and grey, put the lighter color on the wall first. Perhaps paint the other walls in the lighter color. You could add some white accessories to lift the tone of the room, but don't overdo it.