Just what I experienced
Go to your user page by clicking your name and click the password/security link.
Then ENABLE "Two-step-verification"
[I think you have to enter your current password at some point, so be prepared to do that.]
Go to wherever you receive Sherdog emails., open the message, and copy the code.
The message will tell you what to do next; it's straightforward.
The last thing is that Sherdog will pop up a screen with 10 codes on it. Copy them manually and save them somewhere.
@Substance Abuse @Kowboy On Sherdog I was worried about this thing when it first came up. But when I found about the 30 days aspect, it was INSTANT