How to reach Gorowyn
In order to reach Gorowyn you'll want to take the Guild Hall portal to The Overthere. Once here travel south out of the town and to the Skyfire Mountains zone line (on the western end of the zone). This zone is laid out exactly like the old Overthere, so you should be able to get around pretty easily.
Once you're in Skyfire Mountains travel almost directly north following the wall until it opens up at the eastern tip. This is where you will find the entrance to Gorowyn.