Gorten will work for three of the five Mercenary contracts currently available: The Four Star Syndicate, The Highborn Covenant, and the Searforge Commission.
First, you should check out the three contracts and see which one appeals to you. This mostly boils down to "what other models do I want to use?" as not all mercenaries will work for all contracts. Searforge is the "dwarven themed" contract and is a good place to start based on your purchase.
Check out Battlecollege for some good general beginner-level information on these contracts and to see who will work for what contract.
Here's the link to the Mercenaries section of the site.
There's also a ton of useful info in
THIS THREAD on the Privateer Press Forums. I'd cross post it here, but it's freakin' long.