You may not post data to the api but retrieving data in c# is quite simple.
Create a project and get an api key. To get started, just make use your project's name, whatever it is and your profile url as the app's website. This information can be modified at any time in the future.
Either build or add a project reference to Soapi.net35 or Soapi.net40 to your project
and from there, it is quite simple
var context = new ApiContext(apiKey).Initialize(false);
var site = context.find("http://stackapps.com");
var skysQuestions = site.Users.ById(14).Questions.ToList();
foreach (Question in skysQuestions)
The current version of the API is read only, meaning you can not have users login and post answers/comments/questions. Theres documentation on the API, which you can get by click on the API documentation and help just here on the right column >>>>