One: Have a circular saw and a large nail gun. (Also a square, a measuring tape, one of those flat pencils, and a medium sized step ladder.)
Two: Order several pallets of really long boards in various sizes and a bucket of nail gun nails from Menards.
Three: Cut the boards into shorter lengths and, using the nail gun, nail them together in the shape of a garage.
It helps, of course, if you actually know how to build a garage.
