Not sure what the problem is.
HDMI carries audio and video. Can't be plugged in the wrong way. Cable box will only have one HDMI jack. Select any HDMI input on the TV. If the TV has an HDMI-ARC input don't use that one since you may want to use it for a soundbar or surround sound system later. If you don't care about that then it will work fine like all the other HDMI inputs.