Inserting Google Calendar events using c#.NET Winform

I've written a small application and one of the requirements is to allow Users to add events to their Google calendar using my application.  I've been browsing the net and have tried several examples, but I keep getting an "invalid credentials" error. I'm missing something in the code and I've yet to figure it out. Any help or suggestions would be great.

Thanks in advance.

sample1.txt