Ajax with .net

I want to use Ajax with .net.Can anyone suggest me how can i learn Ajax with .net?

https://learnable.com/courses/jquery-fundamentals-1132

Lesson 6 details Ajax, though doesn’t really address server aspects. Which framework are you using ASP.NET or MVC?

There is also a toolkit called Ajax Control Toolkit from Microsoft, you can learn more from their website ASP.NET AJAX Control Toolkit

Another link to look at:
ASP.NET and AJAX | Nettuts+