Hi , 
I am working "Create And Update Google SpreadSheet Via Google API.NET Library" help of 
 https://www.c-sharpcorner.com/article/create-and-update-google-spreadsheet-via-google-api-net-library/ 
tutorial.
but in this tutoral  excel sheet id is fix, thats by my hole data upload in single sheet, but i want evey time when i downlod the data its write in diffent sheet. please guide me.please