29x21cm-2019-0921 The circle part of the picture below: you need connect them with screw M6*10. The back side is repeating the above options; you get the complete frame of our product. STEP 4 You need a cover part ) Put the cover over the frame, and stretching the cover. Make sure each edge on the cover's side are match the edge on the frame. Finally you get your job done: GREENHOUSE INSTRUCTION Thank you for your purchase.