u/Shinobi-King18

I'm currently in the Whoreson quest and trying to play in the casino since I have to win a few games to get to the higher floor. Problem is, I can't win a single game of Gwent. I've bought every card I could from Velen, I've read the rules, but nothing clicks. Can someone fill me in? I even have the special cards from the settings mode on, but I just don't get it.