Hi,
To be strictly correct,
you should remember that a Sequence Diagram is a dynamic view of the application, so, you must show instances unless your class has static methods.
But if you follow Mark Cade�s example you will be fine. I havent gotten my results yet, but I followed his advices, as others ranchers have done.
Cleuton Sampaio<br />Systems Architect<br />(SCEA,SCWCD,SCBCD,MCSE,MCSD)