It's basically a virtual board with everything you need. Make a user, probably a good idea to pay the $5 it costs to have premium for 3 months and make your own army. It works great if you play with someone you can talk to on Skype. I'd be up to play with people although it we'd probably all be quickly bored if we only played mirror matches
I knew it but i've never tried to learn how to use it, sadly! One day I'll learn and hopefully I'll have the chance to play with far fellows haha