Procedure:
1.Open a model
2.In the Weldments toolbar click on Structural Member or go to Insert 
Weldments Structural Member
3.Click to calculate the joints
•Pink joints indicate the joints where two or more structural members intersect
•Green joints indicate the joints are a free end of a structural member
4.To edit or modify a joint, right click to highlight the members that make up a joint
•To add a member to the joint, just select a member not highlighted
•To delete a member from the joint, select a highlighted member