Shovel fill soil into any holes and low-lying spots.
Spread and even out the soil in the low-lying areas with a rake.
Tamp down the fill soil with the back of your shovel. Add more soil if necessary and even it out again with the rake.
Dig up any smaller bumps in the yard using a shovel. Dig into the bump on three sides and extract dirt from underneath the sod. Then lay the sod back over the area that you dug. This will help to preserve the grass in these areas. If you aren't concerned with preserving the grass, simply dig up the bumps and toss them away.