Decide on the bed size. The ideal width is 4 feet, to allow easy cultivation from the path, but beds can be any length. Cut four edging boards to the correct length and nail on wooden pegs about 4 inches from the ends.
Lay out the boards in their final positions and drive the wooden pegs into the soil with a mallet. Check that each timber is straight using a level, making adjustments by pounding the higher end down with a mallet.
Rest a piece of wood diagonally across two edging timbers, place a level on it, and make any necessary adjustments. Before building another bed, ensure that you leave a path wide enough for easy access.
Fill the bed with good-quality topsoil that has been improved with organic matter, such as garden compost or well-rotted manure. Spread the soil evenly and level the surface with the back of a rake. Top off as the soil settles.
Make sure the soil is level by stretching a length of string across the raised bed. Bricks will keep the string taut.