Publishing on Facebook user's wall

i am developing an appon blackberry platform in which i hve to publish a message on users wall...i am able to get session id...but dont know how to proceed further...

i am doing something like this...

enter code here
URLEncodedPostData post = new URLEncodedPostData(URLEncodedPostData.DEFAULT_CHARSET, false);
        post.append("method", "stream.publish");
        post.append("message", "published through the Facebook API");
        post.append("session_key", 开发者_Python百科sessionKey);
        post.append("attachment", null);
        post.append("action_links", null);
        post.append("target_id ", null);
        post.append("uid ", null);

i am sending this as post data to following url :

        http://api.facebook.com/restserver.php?

and the response i am getting contains : 101 Invalid API key

You should try to register your application, get API key and use in in requests.
Register and go www.facebook.com/developers/createapp.php