Lay out a garden hose along the edge of the gravel area that you would like to contain. This will define the edge as you prepare the foundation for the landscaping edger installation.
Cut into the soil approximately 6 inches along the outside edge of the garden hose, using a shovel.
Place a landscaping edger along the outside edge of the cut soil. Align the hose along a parallel line with cut soil to represent the width of the landscaping edger. Set the edger aside. Cut the soil along the inside edge of the garden hose with a shovel. Set aside the hose and dig between the cut edges to a depth of 6 inches.
Fill the bottom of the trench with enough sand so that one-third to two-thirds of the edger will be above ground level.
Lay the edgers end-to-end on the sand along the entire length of the trench.
Place a level across each edger. Add or remove sand below the edger to adjust the level. Tap the edger into place with a rubber mallet, once it is leveled. Continue this process until each edger is level along the edge of the gravel.
Fill in areas that have thin gravel with fresh matching gravel. Use a bow rake to rake the gravel even.