Dig out 6 inches of the grass and dirt in the area where the pavers will be installed. Place the dirt in a wheelbarrow for removal.
Cut strips of landscape cloth to cover the bottom of the excavated area. Lay the strips on the bottom and overlap individual pieces by several inches.
Lay 2 inches of medium gravel on the bottom of the excavation. Smooth the gravel with a heavy rake.
Lay 2 inches of fine gravel on top of the medium gravel and rake it smooth.
Fill the excavation with sand to within 1 inch of the top. Compact the sand with a heavy roller. Place more sand and compact until you have firm base of sand that's 1 inch below the top of the excavation.
Build your paver wall on top of the foundation you've built.