Position the wooden boards end to end to form a rectangular shape. The shape will be 8 inches high and 24 inches wide by 26 inches long.
Place one 4-by-4 inch post in each inside corner of the rectangular shape. Four inches of each post will stick out above the tops of the boards.
Attach the posts to the boards, using four screws on each end of the boards. Drill the screws through the boards into the posts. You'll use a total of 32 screws, eight on each board.
Turn the boards and post over, so that the shape stands on the bottom of the posts, which form the legs of the ottoman chair.
Set the remaining wooden board on top of the ottoman frame. Align the four sides of the board with the four sides of the frame, then drill two screws into the top of the board at each corner to attach it to the posts.
Cover the foam with the fabric, bringing the ends of the fabric under the bottom of the foam. Pull the fabric so that it is taut and smooth.
Hand-stitch the ends of the fabric together with needle and thread. Pull the thread tightly to keep the fabric taut. Trim away any excess fabric and thread.
Coat the top of the ottoman chair with the fabric glue. Center the foam and fabric on top of the frame and press. Let it dry overnight.
Paint the wooden frame of the ottoman chair, while the fabric glue dries. Be careful not to get paint on the fabric and foam.