These stairs fit into a natural landscape well and are easy to make.
Step 1: Start at the Bottom
You will need 8 x 8 pressure treated posts, end cut, and 10 inch galvanized spikes. Remember to paint any cut ends with end cut preservative. To begin with, you should lay a board or run a string all the way up the slope where your stairs are going to go so the stairs will be straight.
Start by cutting two pieces of 8 x 8 post two feet long and another piece as wide as you want the stairs to be. I have done stairs three feet wide to eight feet wide. Make a "U" by nailing the two foot long "stems' of the U onto the width piece using the 10 inch spikes.
Level the ground at the bottom of the stairs and place the U on the level part with the stems pointing towards the rise.
Step 2: Continuing the Steps
Make another U the same size. Dig out a place for the stems of this U that is level with the top of the last U. Slide the second U on top of the first U so that it is 16 inches in from the front of the first U. This distance of 16 inches will become the "run" of your steps. You can make the run as little as eight inches but larger runs give a more open feel.
Hammer a 10 inch spike through the stems of the top U into the bottom one, one on each side. Continue making U's and adding them on top of each other until you reach the top of the slope. Remember to keep it straight by lining up each step with the board or string running up the slope.
Step 3: Fill in the Steps
Fill in the steps with the dirt that you dug away as you were leveling each step. As this is pressure treated wood, you don't need to paint or preserve them but you can if you'd like.
Grass and weeds will grow in the filled in portion of the steps. If the stairs see a lot of traffic, it will keep the growth down. Alternately, you can put wood chips or gravel instead of dirt or just cut the growth every once in a while.