Questions about MMO

Hello guys all i want to know what are things that i need to learn for making MMO games. What you prefer for an engine or stuff like that. I was going in making the use of nuclear glory software and ms visual studio 2010/2013.
Can anyone direct me in the right path?

We making a card game :https://www.facebook.com/pages/Eternal-World/1469321193318141

Basically i want to learn the things needed for that game. It is an MMO card battle game like heathstone/rage of bahamut/devilmaker...

Questions about MMO