From the Modify drop-down menu, and down to .. 3D Operation, then the fly-out .. Click on Align. The cursor turns to square. From the Modify drop-down menu, and down to .. 3D Operation, then the fly-out .. Click on Align. The cursor turns to square.

 Now, click on the truss block (B) and then right mouse click for enter.. Now, click the mouse at location (1) on truss (B) ... Next, click the mouse at location (2) on truss (A)

Now, click the mouse at location (3) on truss (B) and click the mouse at location (4) on truss (A)Right mouse click for enter ....