I think this article might help.. Are you plugging them in correctly? https://www.howtogeek.com/174452/beginner-geek-how-to-use-multiple-monitors-to-be-more-productive/
I've got multiple monitors right now. For me, you have to plug in both of your monitors into the video card and not the motherboard.
Setup to monitor where/for what? For general usage, just plugin the monitors into your video card ports (as far your card has more than 1 port and you have the cables) For games? With a Nvidia GPU you have to use the 'Nvidia Surround' thing (never figured how it works). For AMD, I think it's eyefinity (don't own AMD card)