Bad news my friend, Google Drive doesn't support FTP as a means of uploading a file. They also don't accept credentials directly in the web request as you have done. They only support OAuth connections. There is a number of security related reasons for this.
I wrote an article a long time ago (
Working with Google Drive in WPF[
^]) that covered the scenario you are trying to do. However... Google has since deprecated that API so you can't use the code in the article but the authentication workflow is essentially the same which will help you understand the steps required.
At the time I wrote that, there was no API client library for .Net from Google. That has changed. You can download the client library and view a sample at
Drive API Client Library for .NET | API Client Library for .NET | Google Developers[
^] That library should let you just drop-in support for Drive in your application. It is even available as a NuGet package directly from Visual Studio:
Google.Apis.Drive.v3 on NuGet.org[
^]
I'll say however, that this might be a daunting task for someone new to C#. If you go looking for information, make sure it applies to the latest Google APIs. Drive has been around a long time and Google has changed the APIs at least twice before. (My article was written against v2 of their drive API.) Since Google and other web sites never forget, you might find a lot of out-dated information.
Good luck!