To build a retaining wall, gather materials, plan the wall's layout, dig a trench, stack the blocks, and then backfill. If the wall requires a water runoff pipe, install this before the backfill.
Gather the materials for the wall first, and then use a water hose to lay out a line for the wall, marking it with tiles. Along the line, start digging a trench that is slightly wider than the chosen blocks and deep enough so that the first level is just below ground level. Tamp down the bottom of the trench with a tamper, ensuring it is level, and then add several inches of ruck dust and gravel.
Start at the most visible edge of the wall, and position the first stone inside of the trench. Make sure it is level by using a line level and string. Continue laying the stones along the trench until the first level is complete. Start the next level a bit offset from the one below, and keep layering the stones as the wall gets higher. Periodically check to ensure the stones are level and do not wobble.
When the wall is at its tallest height, place landscape fabric against the back of it, and then begin backfilling. Backfill in layers, beginning with gravel, and then use fill dirt. Make sure to tamp down each layer before starting the next. The final layer should be topsoil.