How to Get Surface from Generic Model and relunch to Revit

I am tring to create surface from a generic model for hours but I couldnt manage.And I tried Dynamo , ı can select generic model face and crate surface area on dynamo but this time couldnt manage to importing to revit.When I open a new conceptual mass fiile I get error Dynomo is not pointing at the current document.Please help me for god sake .
I’m gonna go crazy.