Portable Monitor/iMac Connection Issue

Hi, I have a GeChic 2501c portable external monitor that I use at work with a pc (I'm in consulting).

I had some wacky idea to use the monitor at home with my iMac (mid 2011 27") and I can't get it to work. Here is what I have tried:

1. Bought USB to HDMI adapter, and plugged monitor hdmi cable into the adapter and also plugged in power cable, and I have a black screen. The power is working.

2. Bought thunderbolt to HDMI adapter, but it doesn't work with the hdmi cable because that creates a male to male situation.

My primary use at home is just work, bills and surfing, so I'm not concerned about sound or video.

Any ideas?