To post a map to bungie.net simply upload it to your fileshare. If you want them on forgehub go to the respective tutorials on how to upload pictures and show a map. I wish you luck!
You can't. If you are thinking this because of the way the rule is worded, don't worry about it. The link to your map must send you to the map on your fileshare on b.net. Not your actual fileshare. So when you make your map thread just put the map on your fileshare, click on the map on b.net, and copy & paste the link here. Man that rule really needs to be re-worded.