Using the line-marking spray paint, mark out the shape of the bed. For straight lines, tie a piece of string to two wooden pegs, secure the pegs in the ground, pulling the string taut, then spray along the string. For curves, tie a piece of string to a pole, pushing it into the ground at an equal distance between each end of the curve. Pull the string taut and mark where it meets one end of the curve. Walk the curve, keeping the string pulled tight, and spray. Leave the pole and marked string in place.