Welcome to Android Central! Where do you see the 1 GB on the computer? Are you sure you're selecting the actual S6 device, or is there a "CD Drive" associated with the phone? Don't click the latter, since that's a small unremovable partition that contains some (mostly useless) programs from either the manufacturer or the carrier that you can install to the computer (like sync programs).
If you don't see a CD drive, and you are in fact clicking on the S6 device in Windows Explorer, then I would wonder if you have a clone or counterfeit S6. Show us a screenshot of the
Settings>Storage menu on the phone:
http://forums.androidcentral.com/amb...d-central.html