please provide me documentation on building a server app on c#

Here the thing first decide what sort of servdr technology in C# you wants to work with i.e. ASP.NET MVC, ASP.NET Core. Then you can explore C-Sharp corner learn section to develop a web app. You also need to consider that that do you want to build a webseite or a Web API before you jump in the coding.

 

Here is the quick link to ASP.NET MVC zero to hero development guide -> https://www.c-sharpcorner.com/learn/learn-asp-net-mvc-50

 

 

 

@Arijeet,

Can you elaborate more, which server app you want to build? 

 

If you want to create remote server app, follow the link:

https://docs.microsoft.com/en-us/troubleshoot/developer/visualstudio/csharp/general/create-remote-server

 

If you want to create client/server app, follow the article:

https://codeabout.wordpress.com/2011/03/06/building-a-simple-server-client-application-using-c/