Trying to hook up a device like a DVD player with an AUX output that has the red, white and yellow phono plugs to a television that only has a coaxial connection cannot be done without the use of an RF modulator. The cable you use that goes into the phono plugs is called an AV cable. It is a connection designed to separate the right and left channels of the audio and gives the video it own path. A coax connection has all the information stuffed into one cable.
Plug one end of the A/V cables into the AUX output by matching the colours on the plugs with the colour of the outputs.
Plug the red and white plugs on the other end of the A/V cable into the red and white "Audio In" on the RF modulator. Plug the yellow plug on the A/V cable into the "Video In."
Twist the end of the coax cable, which is called an F-connector, onto the connection marked "To TV" on the RF modulator.
Twist the F-connector on the other end of the coax cable onto the cable connection on the back of your television.
Plug the power cord on the modulator into your wall outlet.
Turn your television to channel 3 and select channel 3 on the channel selector on the front of the modulator. If the picture doesn't come in clear, switch your television to channel 4 and flip the switch on the modulator to channel 4. Decide which channel will give you the best picture.