You can build your own shed trusses because small sheds usually don’t require permits and therefore the trusses don’t need to be engineered.
Trusses are typically built with 2×4’s and installed either 16 or 24 inches on center. Depending on the shed design and roof load. In addition you’ll need a truss for either end of the shed which will be attached with sheeting and become part of the end walls. I have more information on building shed trusses in my FREE Shed Building Guide.
A shed roof will have rafters. A rafter is a single beam where as trusses are multiple beams tied together with a cord or gussets. A gable roof truss will consist of 2 beams and a cord or gussets. The cord or gussets are what keeps the beams from spreading apart and give the truss it’s strength. A gamble roof truss will consists of 4 beams and 3 gussets.