For some reason the mount/burn options didn't show up for me when I highlighted the .iso under Manage at first either. There were no Manage or Library options at all when I first tried this.
I had to double click the .iso at which point you can see it virtually mount into the DVD drive at Windows Explorer>under Computer.
After that I right clicked the drive and ejected the virtual mount.
The next time I highlighted the .iso, the mount and burn options magically appeared under Manage.