Facebook - Sharing something

Hello,

I have an issue with my app.
I want to share something on facebook but I don't know how to do it with xamarin.auth.
I think I have to use this sample, but I don't know how to change it to do what I want :

var request = new OAuth2Request ("GET", new Uri ("https://graph.facebook.com/me"), null, eventArgs.Account);
request.GetResponseAsync().ContinueWith (t => {
    if (t.IsFaulted)
        Console.WriteLine ("Error: " + t.Exception.InnerException.Message);
    else {
        string json = t.Result.GetResponseText();
        Console.WriteLine (json);
    }
})

If somebody know I do it, it would be cool.