If you have a character that has a lvl 3 Garrison you have the opportunity to develop a shipyard (The shipyard is basically a lvl 4 Garrison).
After launch of 6.2, when logging on, your faction leader will be in your Garrison to handle you the first quest of the Shipyard development quest chain.
This quest chain will first take you to the iron docks north of Gorgrond (behind Blackrock Foundry). The goal is to free the Iron Horde Shipwright (Solog Roark Horde) and recruit him to help you build your Shipyard and to achieve the blueprint for the shipyard.
When finishing this quest chain you head back to you Garrison and can start building your shipyard.
The shipyard costs 150 Garrison resources and 150 gold, to start building it (Quest: All hands on Deck).
When shipyard has been completed you will have a new quest to start the built of a ship (Quest: Let´s get to work).
This quest wants you to talk to Shipwright (whom you saved before). He will provide you with a blue print for a transport ship (for free) (Quest: Let´s build a ship).
But to build the ship is not for free. A transport ship costs 1000 Garrison Resources (Quest: Ship Shape)
Ships are like the followers. There are uncommon, rare and epic ships.
They can proc various rarity, meaning you can get a blue rare ship directly
When coming this far in the shipyard quest line, you can now speak to Khadgar to start your journey to Tanaan Jungle.
Good to prepare yourself with 1150 Garrison Resources:
150 Garrison Resources (for Shipyard creation)
1000 Garrison Resources (for creating your first ship)