Step 4:
Fig. 7: Insert Corner bottom beam (E) into Side pole 2(D).
Fig. 8: Insert Side pole 2(D) into F.
Fig. 9: Insert Support pole 2(H) into Support pole 1(G).
Fig. 10: Insert Corner upper beam (F) and Support pole 1(G) into Top connector (I).
Fig. 11: Insert Corner bottom beam (E) into A1 (B1).
Fig. 12: Connect Support pole 2(H) and Side pole 1(D) by Screw (AA) and Washer (BB).
