Easiest way is in the URL of an http request - like this (I'm logging
fisheries catch data back to the server):

   protected boolean sendQueueable( Queueable q )
     throws IOException
   {
     boolean result = false;

     if ( q != null )
     {
       HttpConnection hc = null;
       InputStream in = null;
       StringBuffer url = q.getURL( new StringBuffer(  ) );

       hc = (HttpConnection) Connector.open( url.toString(  ) );
       in = hc.openInputStream(  );

       int response = hc.getResponseCode(  );

       switch ( response )
       {
         case HttpConnection.HTTP_OK:
           showMessage( MESSAGETYPECONFIRM, q.parseResult( in ) );
           result = true;

           break;

         case HttpConnection.HTTP_UNAUTHORIZED:
           showMessage( AbstractFieldKit.MESSAGETYPEERROR,
             getConfig( "FieldKitMidlet-MessageBadAuth" ) );