You can get them as drops, By doing certain epic battles. Click this for list of epic battles, and their drops. You can also buy them, Using mith as a form of currency. Post Questions Here next time.
Mithril can be earned by wars and you can buy a limit of 6. The cheapest equipment costs 50 mithril. But you can always get then from easy epic battles (EBs) like the reckoning or origins