Place structural truss elements in your model.
Truss layouts transform to fit the full span of the truss, creating framing elements that correspond to the lines in the transformed truss layout.
 Structure panel
Structure panel 
  (Truss).
 (Truss).  Draw panel
Draw panel 
  (Line) to specify the start point and endpoint for the truss, or click
 (Line) to specify the start point and endpoint for the truss, or click  (Pick Lines), and then select an edge or line to which you want to constrain the truss model.
 (Pick Lines), and then select an edge or line to which you want to constrain the truss model.