The CookieAwareWebClient is a simple wrapper on top of the WebClient. Thus, you use it like you would normally use the WebClient class, with the notable exception that the CookieAwareWebClient accepts and optional file name, declaring where in your IsolatedStorage
you would like to save the serialized cookies.
WebClient client = new CookieAwareWebClient("cookies.txt");
client.OpenReadCompleted += (sender, args) => args.Result.Close();
client.OpenReadAsync(new Uri( ... ));
The CookieSerializer is used internally by the CookieAwareWebClient. The best usage example I can think of, is the usage in that code. Please have a look. :-)