Как разместить на своей странице в Facebook, используя Facebook SDK?

Попробуйте использовать backgroundworker .

private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
   //Helper thread: Long during task
}

private void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    //We're in the main thread: Show your messagebox
}