What you need..
poster board with boarder
Tape frame around the middle of the poster board.
Paint one, or two, coats of primer. Waiting until dry between coats.
Paint a coat of chalkboard paint. Let dry and paint another coat. You may need to give an additional coat if you see any bare spots. Remove painters tape. Follow directions on chalkboard paint can to write on board. <3 and hUgs!