Well, to get to Netherstorm, you must go through the bridge on the Western side, from Blade's Edge Mountains. You obviously just travel like other places, but there is one difference: It is seperated into land pieces. At some sides of these land pieces, there are bridges, that lead to a nearby piece of land. There is 1 spot in the Northern part of Netherstorm that you must have a flying mount to get to. The rest of the land pieces have bridges to easily travel to the next.