How do I hook up my comcast coaxial tv box to a monitor that only has hdmi ports?

I get free cable with my business, but I have a coaxial cable coming from my wall, but I only have a Samsung monitor (no speakers) that doesn't have a coaxial cable barrel port on the back. The TV is 50 ft away downstairs and the modem is upstairs. How do I hook it up?

Comcast gave me this little box with coaxial cables on the in/out but with no hdmi output..Front of boxBack of box, no HDMI to TVPart # Serial, etc...