Well you need to find all parts of ship, most of them should be in wywern nest's also few of them are at cliffs. Just get dragon form and search exactly fjords.
Once you have at least one of each of the 3 different types of zeppelin parts (rudder, compass, crystal), you can turn them in to Page at the harbor's zeppelin pad, then talk to Sepp on the ramp to go to Aleroth.
