You will likely need to find the proper input, as the above poster said. From there, you will be able to use your cable remote to tune into the channels you would like to watch.
If the coax cable from the wall goes straight to the TV then select QAM tuner on the TV set up menu and run a channel scan. You will only detect unencrypted channels.
If the coax cable from the wall goes to the cable box and that is connected to the TV with a coax RF antenna connection then usually channel 3 or 4.
If the cable box is connected via HDMI or AV connections to the TV select that input on the TV.
I have a old sharp TV I have the ground cable Cord run to the cable box and other cord run from the back of the TV to the cable box I am not seeing a picture but I can see me changing the channel on the TV but no picture