We can't answer that - it's far, far too broad a topic.
Start with Google:
anti forgery token in asp.net C - Google Search[
^] - follow some of the links, start reading, and think about how it applies to your requirement.
If you have further questions after that, first try googling them, and repeat until either you understand or bring the confusion down to a level we could possibly help with.
Submit an article or tip