When you want to make a bed you can use marker paint to mark the shape of the bed. After you remove the grass you put in topsoil mixed with peat moss. You want to use a flat "D' handle square sharp spade shovel to make a clean straight flowing edge around 3 inches or so deep. You want the soil and mulch to curve down to the bottom of the edge so you can see the 3 inches of edge. This will give a defined edge and you want to turn your weed whacker upward so that you can shave the 3 inch edge for a clean sharp manicured look.