STEP 1:

Begin front wall assembly by nailing plate board (C) to the bottom of corner posts (A). Place center post (B) in the middle of plate board (C) and nail through (C) into the bottom of (B). Repeat Step 1 to build back wall assembly.
NOTE: Unless specified, all nails are 12d. Or you can substitute screws for nails.

STEP 2:

For back wall, nail bottom rail (D) to corner posts (A) and center post (B), flush with edge of bottom plate (C). Nail top rail (D) to corner posts (A) and center post (B), placing it 4 inches from top of corner posts (A).

STEP 2A:

For front wall, nail bottom rail (E) to corner post (A) and center post (B), flush with bottom plate (C). Nail top rail D to corner posts A and center post B.