Quick & easy:
1. Glue together wooden balls of different sizes, as wide as the inside dimension of the frame. Make sure that the holes point upwards and downwards so that you can put the dried flowers through them later.
2. After drying, fix the wooden balls in the frame with hot glue.
3. Select the dried flowers, shorten the stems and insert them into the wooden balls.
4. Select a paper from the paper block, cut it to the size of the wooden frame and place it on the back wall. Finally, fix the back wall in the frame.