It starts with the guy in Ratchet. All you have to do is hit 200, then you have to go visit the guy in Gadgetzan. Once there he will require you to make the following:
x20 Solid Dynamite
x10 Big Iron Bomb
x5 Explosive Sheep
After that, he makes you sign an agreement saying you are an official Goblin Engineer, and therefore you can only look at Goblin schemata. After that he hands you your card which has a lifetime of 14 days of GAMEPLAY. Not 14 days of real time, but 14 days of gameplay. Every 14 days you have to have it renewed, which costs ... was it 2G or 5G?
Anyways, just be sure to have the items with you when you go. It'll make it a lot easier. Being lv. 60 you should have no problem getting the items, whether through buying or harvesting.
I did this quest at lv. 30.