So the netcode is pretty bad, but will get an update on October 4th that will improve not only netplay, but add Kombat pack 2 characters (aka...the "XL" update). Anticipate a boom in player population, and a lot of triborg/Alien players.
You can just hop into a quick player or ranked match and hope you get a match, or invite a friend to play with you. Win the match, don't let the other player ragequit. Does not count it if the internet drops you or the power goes out.
I have a bad schedule, but I'll play with you if you catch me playing. Otherwise, hit the Gaming Sessions section of the page (under "community" above) or check the Steam community page.