C#-Facebook-SDK WP7, the principles of how Facebook works?

Apologies if this is somewhere, but I'm struggling to find the details I need for wp7.

I have created the application on Facebook as required, and am retrieving an access token. The following code posts to Facebook but I cannot get a response, nor can I work out how to monitor the response?

public bool fbUpload(string accessToken, Picture pic)
    {
        try
        {
            Stream s = null;
            s = PicturesLoader.LoadFileFromStorage(pic.Url);

            //Sets the byte array to the correct number of bytes
            byte[] imageData = new byte[s.Length];

            s.Read(imageData, 0, System.Convert.ToInt32(s.Length));

            FacebookApp app = new FacebookApp();
            IDictionary<string, object> parameters = new Dictionary<string, object>();
            parameters.Add("access_token", accessToken);
            parameters.Add("message", "TEST - WP7 application [upload pic and comment on wall...]");
            var mediaObject = new FacebookMediaObject { FileName = pic.Name, ContentType = 开发者_如何学编程"image/jpeg" };
            mediaObject.SetValue(imageData);

            parameters["source"] = mediaObject;
            FacebookAsyncResult postResult;
            FacebookAsyncCallback fbCB = new FacebookAsyncCallback();
            app.PostAsync(parameters, fbCB);



    return true;
        }
        catch (InvalidCastException ex)
        {
            return false;
        }
    }

The other question I have, is how do you allow users to allow access based upon their own Facebook account. I want to store a user's account details so they only have to set up the account details once, and then they can use my phone app with having to sign in?

You can handle the post result something like this:

FacebookAsyncCallback callBack = new FacebookAsyncCallback(postResult);
fbApp.PostAsync(parameters, args, callBack);  

private void postResult(FacebookAsyncResult asyncResult)   
{
  // Do something with asyncResult here;
}

Regarding the second question, you must ask for permissions to access this data. You usually do that in the FacebookOAuthClient.GetLoginUrl(<appId>, null, <permissions>) method call.
Once that's done, you can store the files you have permissions to locally in your app.