Computer Techy Needed.one time

I need someone to help me set up 3 monitors. I've got 2 now. I have only 1 HDMI port. I bought a USB 3.0 to HDMI adapter to try to gain access for more. I'm getting no signal on 3rd monitor. I might need a graphics card updateor something else. Black [blinking] boxes tell me refresh might be slow. This job will be easy for someone.with more tech skill than me. At least one hourmaybe 2. Thanks.