Ideally your composter should be installed into the ground and not simply placed on top of the grass.
Start by cutting a circle of turf the same size as the base of your composter.
Work around the base with a space cutting to a depth of no less than 5 inches.
Remove the sod in sections.
Dig the exposed earth to loosen and break up compacted soil.
Place the composter into position.
Replace the sods to fit snuggly to the composter.
Press down each sod, remembering to leave a gap for the hatch.
Now add your organic waste. Make the first layer from brown organics (leaves/hay/straw/newspaper). Then simply dispose of organics as you generate them.