To add an instance figure to a sequence diagram, follow these steps:
Select Attach from the pop-up menu of the new object figure. A window appears listing the available class designs.
It is important to remember that objects in a sequence diagram are instances, not classes. Therefore, when you select a class design to attach, UML Designer automatically creates a new anonymous instance of the selected class and attaches the figure to the new instance.
If you want to use a named instance rather than an anonymous instance, deselect Is Anonymous on the instance figure's pop-up menu. You can then select Rename to change the name of the instance. (If you rename an anonymous instance, Is Anonymous is automatically deselected.