Cable signals are generally sent by cable companies to televisions through the use of a coaxial cable. While this cable is capable of sending high-definition (HD) signals to HD televisions, the signal must be converted from the coaxial cable to a signal that an HDMI cable can carry to the television. If you wish to convert your coaxial signal to an HDMI signal, you can do so with an HD cable box.
Connect one end of your coaxial cable to a coaxial wall port near your television. Connect the other end to the input coaxial port on your HD cable box. Plug your HD cable box into a power socket.
Connect one end of your HDMI cable to the HDMI output port on your cable box. Connect the other end to the HDMI input port on your television.
Turn your television on and change it to its HDMI input channel. You should now be able to see the signal carried by your coaxial cable on your television screen.