Measure the distance and height of the hill to determine how many steps you need to build. Landscape timbers are 6 by 6 inches, so the height of each step should be divisible by 6.
Dig out enough of the hill to place your sleepers, or the two pieces of timber on either side of the step that holds the stair in place. At the bottom of the slope, remove enough dirt to set the first step.
Use a circular saw to cut the timbers to the desired height and width of your steps. Consider making your steps 4 feet wide so you can simply purchase 8-foot timbers and cut them in half. For instance, you'll need one 4-foot-long timber for the front of the step, and two 4-foot-long timbers for both sides of the steps.
Arrange the three pieces of cut timber on the ground, and use an angle brace on the front interior of either side.
Put two 10-inch spikes through the front and into 3/8-inch holes in the side timbers.
Excavate enough dirt from the bottom of the hill to place the first step. Place the second step on top of the back of the bottom step. Drive a 10-inch nail spike through the front of the second step to secure it to the back of the bottom step.
Place each additional step as you did the second one, attaching them with a 10-inch spike and using a level on each step to ensure they are even.
Fill in the steps with landscape rocks or pavers to support the timber frames and provide an even surface at each level.