StackOverflow, When ever i'm developing something, stackoverflow always saves me when needed.
C# also has alot of documentation and videos so a simply google search or youtube search for c# tutorials and you'll be on your way, I was able to get a good understanding and make a simple game with c# from scratch with around 7 days of 8+ hours a day.
Add me on steam and message me if you need help or questions, usually always free.
steamcommunity.com/id/AnonGaming21/