Sort through the rocks and stone before creating the wall. Divide the rocks based on size, as the larger stones provide more support than the smaller ones. Go through each pile, dividing the pieces according to shape within each size group.
Create the outline of the rock wall with garden hoses. Twist or bend the hoses into the shape you want for the finished wall. Trace around the edges of the hoses with a shovel, marking the shape, and remove the hoses.
Make a trench that runs the length of the wall. Dig between the markings you made in the last step. Remove the top 8 inches of soil and grass. Go along the edges of the wall, extending the trench 2 inches wider than the original markings for more stability.
Cover the bottom of the trench with compacting gravel, which contains a mixture of crushed rock and smaller stone. Use as much gravel as it takes to fill the trench halfway full. Spray the gravel with water and pat down the top, making the base more solid.
Arrange the larger stones on top of the gravel. Once you have the first layer in place, arrange a second layer on top. Overlap each stone, as you would when laying bricks. The top stones should sit equally on two stones underneath. When you reach the top of the wall, cover the top layer with square or rectangular rocks.
Go over the rock wall, looking for gaps between the stones. Fill in those gaps with a small stone inserted in the middle. Hit the stone with a hammer until it slides into place. Pour new soil along the front and back of the stones, filling in the gap between the trench and the rocks for extra support.