Hi testingemail11042024,
The error you are getting because you are trying to access non-static member like field, method or property without an instance of the class.
So, you need to create instance of the class to access the non-static members.
Why are you not using Session? The article you are reffering used Session to pass parameters to the PostFile method.
GoogleConnect.PostFile(code, (HttpPostedFile)Session["File"], Session["Description"].ToString());