The quantities needed for each of these 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.
Start by building the base and internal structure of the oven. The first step is to measure the outline for the base and set with cinder blocks. The key to building the block is to check level often and you use plenty of mortar.
Once the oven's structure is chest high, saw grooves in the block and cut rebar to lay in a crisscross pattern. This will create the foundation for the oven floor when the concrete is poured. Put in 3 inches of sand, cover it with tar paper, and pour concrete over.