The code can get kind of complex, unwieldy and cumbersome. It's nice to have but if you can live without it, honestly I'd say to go without. It's a pain in the ass.
If you're STILL looking to do it, here is how it works:
Code:
[tabs]
[tab=Tab 1]
Content for your primary tab goes here.
[tabs]
[tab=Tab 1.1]
Content for Tab 1.1 goes here.
[/tab]
[tab=Tab 1.2]
Content for Tab 1.2 goes here.
[/tab][/tabs][/tab][/tabs]