In a use case diagram, drag an Extends shape onto the drawing page.
Glue the Extends endpoint without an arrowhead to a connection point on the use case providing the extension.
Glue the Extends endpoint with an arrowhead to a connection point on the base use case.
Double-click the Extends shape to open the UML Generalization Properties dialog box. Add the property values, and then click OK.
Indicate an extends relationship between two use cases