Check with the local building authorities to determine the frost line in your area. The frost line is the depth at which frost does not occur during the winter. It is important to install your concrete footings below the frost line so that cracking and shifting does not occur.
Dig a trench along both sides of the concrete stair installation location. The trenches should line up with the edges of the staircase placement and run all the way from the front to the back of the staircase. Dig the trenches so they end about 12 inches below the frost line. The trench should have a width of about 10 inches from its bottom upward to a point 6 inches above the frost line. From here on up, the trench can open as widely as you like to make the job of laying the footings easier.
Pour concrete into each trench, and use a piece of scrap 2-by-4 to mix out any bubbles so it settles as densely as possible. Pour the concrete until it reaches about 6 inches above the frost line. Use a piece of 2-by-4 as a screed and scrape along the top of the concrete until it is level. Allow the concrete to dry and set completely according to the manufacturer's instructions before moving ahead with the job.
Lay concrete blocks on top of the footings you have installed. Use the trowel to apply a layer of mortar to the concrete, then put a line of blocks, end to end from the front of the foundation to the rear. Apply more mortar and lay a second row directly on top of the first. Lay the blocks hollow side up so they can be filled with mortar once the entire foundation is in place. (
Continue laying the blocks until they rise high enough above ground level to take the shape of the lowest step in the staircase. Fill the hollow centers of the concrete blocks with mortar up to the rim. Scrape off any excess with the trowel, then allow the mortar to dry and set completely according to the manufacturer's instructions.
Replace the dirt that was removed during the digging process and use the compactor to firmly pack it around the concrete and blocks until it is level with the ground around the stairs. Build your wooden forms atop the concrete base and pour the steps.