The quantities needed for the materials vary with your own particular application. Take the dimensions to a local materials supplier, where they will calculate the amount of each product needed. Always wear eye protection and follow proper safety precautions when working with power tools or pneumatic tools.
Map out the design using marking paint and then dig out the patio. Dig holes for the footing for the wall. In this case, the footing needs to be 14" deep. Add rebar for extra support.
Lay out flex pipe and trace the inside line for the planting bed. This is where the double faced sitting wall starts. Using a gas saw, cut out the traced line. Dig a footing for the wall, and start setting it. Dig trenches and lay down electric wire for the wall lights.