Dig a trench a foot wide and at least half the height of the wall. If the wall will be 6 feet tall, the trench should be 3 feet deep.
Lay the largest rocks in the trench first. Fit like edges together and push the rocks close together so they fit tightly.
Fill the trench with gravel or dirt as you place each layer to provide stability.
Place the stones so that each layer is flat and level. Use a level to ensure the border stays level as you build.
Stagger the stones so there are no vertical joints. Continue building until the wall is the height you want. The width of the wall should have an inward slope of 2 inches for every foot of height. If a 6-foot wall is 12 inches wide at the top it should be at least 24 inches wide at the base of the wall for support..
Save the flattest rocks to place on the top of the wall as capstones.