The handy instructional guide on how to build a shed from start to finish with garden buildings direct (www.gardenbuildingsdirect.co.uk) following the simple steps in this tutorial, you'll learn. Part 2: how to build a garden shed roof . building a garden shed. building the frame of the shed floor . the first step of the project is to build the floor frame for the shed. as you can easily notice in the diagram, we recommend you to build the components out of 2