Question: I need to post a text file to a remote PC. I know of one way which is to setup a ftp server on remote PC but i want to map a drive of remote PC to my computer and then post the file there using C#. In other words i want to know how can i share a folder on remote PC with my computer so i can post a file there using C#.

I want to know how network drive mapping is done

Answer: 
Have a look at [knockoutJS](http://knockoutjs.com/), it's MVVM design pattern should be familiar from your WPF experience.
It seems like what you are trying to do is call up to the server without loosing your current page state. If thats the case, instead of having your onclick hit a URL have it call a javascript method that will do an ajax post. I recommend giving this question a read: [jQuery Ajax POST example with PHP](https://stackoverflow.com/questions/5004233/jquery-ajax-post-example)