Now I use Rose 2002 to design my seq diagram, but it does not support that a usecase be added in seq diagram.
The prepare usecase required the price usecase and the payment usecase. may price usecase be used in prepare seq as "Actor"? or the price usecase is used in prepare seq as "stereotype"? such as there is "<<usecase>>" in a square and the square is display in the top of the seq diagram. any reply is appreciated.
This is described here - UML 2 Sequence Diagram Overview
The method of modeling the inclusion of use cases using in Figure 7 is something that I first proposed in The Elements of UML Style although I have no doubt that others use this approach as well. I basically show the use case as a bubble across the top of the diagram, just like any other classifier, and show a message sent to it with the <<include>> stereotype. This is consistent with both use case diagramming and sequence diagramming practices.