you won't see it in firebug cause firebug logs events that have place on your side (client) that mean in your browser. You could track this if you would use ajax then firebug would log it
If you want to check a track of it use tool to control your network for example WireShark. There you will be able to log this request
if you need to use login and password I would recomend you to use cURL. It is much better IMO