The garage foundation will follow the edge of the sidewalk we poured in the backyard.  I dug a foot deep trench 8" wide for the foundation.  The foundation concrete had to had 3 pieces of rebar in it to follow the building code.  The pipe sticking up in the center is for electrical wire to come through the foundation for lights, outlets, and electric heat.  I added two 20 amp circuit breakers in the panel for the garage.