Adding compost to your garden beds is one of the best ways to improve your soil quality, and therefore, your crop yield. Compost adds essential nutrients back into the soil and helps reduce the amount of trash in landfills, according to the EPA.
Turn up the soil in your garden with a spade. Work around the perimeter first, followed by the interior. There is no need to break up the dirt clods now, just turn it up to make it easier for the tiller to work.
Shovel the compost in with the soil. Cover the soil with 4 to 6 inches of compost. More isn't necessarily better, but it won't hurt.
Run a tiller over the ground. Mix the soil up well, to a depth of about 1 foot. Depending on what you're planting, you may want to till a little deeper, though 1 foot is generally enough for most crops.
Plant your garden as you normally would, either with seedling plants or seeds, as you see fit. Add water generously.