How to do it
Lay Out Wall
Spread Landscape Fabric
Lay First Course
Precast block is trimmed the same way other masonry materials are trimmed. If you're using solid block, score the line you want to cut with a brick set and small sledgehammer. Repeated blows will split the block. Hollow-core blocks don't break cleanly. Buy half blocks and smaller blocks to fit where you need them, or cut them with a masonry blade.
Set Remaining Courses
Some blocks have pin-lock systems. One of the most common employs vertical and horizontal pins. Blocks fit over the vertical pins as you lay them. After laying each course, horizontal pins lock the blocks laterally.
Set Up Drainpipe
If your wall is designed with corners, the corner blocks must overlap at the joints to tie the two legs together. Cut half blocks and alternate them with full blocks as shown, following the manufacturer's instructions. Chisel off the lip of the block if it gets in the way. As you place the block, strengthen the bond with a bead of construction adhesive.