Loosen the knob on the handle of the edger/trimmer by twisting it counter-clockwise. Push the lock-release button on the underside of the handle, by the knob. While pushing the button, pull out the trimmer attachment.
Push the edger attachment into the hole in the handle until the lock release button clicks into place. Start the edger by plugging it in, if it is electric, or pulling the start cord if it is gas-powered.
Place the edging blade between the sod and sidewalk or driveway. Squeeze the trigger on the handle to have the blade begin cutting.
Move slowly down the length of the driveway or sidewalk. Keep the edging blade as close to the edge of the driveway or sidewalk as possible to maintain a clean-looking cut.
Turn off the edger/trimmer. Repeat steps 1 and 2 to remove the edger attachment and replace with the trimmer attachment. Start the edger/trimmer.
Hold the trimmer at the desired height of the grass while squeezing the trigger to cut the grass. Move the trimmer slowly over the parts of grass you would like cut.