You mean sample code? There is a chapter in manual with some step-by-step examples: http://www.tmssoftware.biz/business/xdata/doc/web/service_operations_tutorial.htm and http://www.tmssoftware.com/site/blog.asp?post=295 . Do you have any specific issue you are experiencing that I can help with?
About the RegisterServiceType, it's just that in indeed. The point is that sometimes the class or interface is not used at all in your server code and then the linker removed it from the application. So calling RegisterServiceType, even if it's dummy, prevents the linker from removing it.
How is your service operation implemented, how are you trying call it, and what is the error message you get?