which model must do first structure or architecture
Dear a_tawakol2010,
The best place to start exploring programming with the Revit API is provided by the getting started material, especially the DevTV and My First Revit Plugin video tutorials:
http://thebuildingcoder.typepad.com/blog/about-the-author.html#2
Do not attempt to do anything else with the API before working through those.
That will save you a lot of time, effort and pain in the long run.
As to whether you should begin with Architectural or Structural aspects:
Before you start with any programming whatsoever, it is very important to understand the basic usage and best practices in Revit from a user point of view.
Therefore, I would suggest that you learn the basics of the Revit product family before you even think of starting to program it.
I hope this helps.
Best regards, good luck and have fun!
Jeremy
