How to program a television for "closed caption"?

My mother is 92 years old and deaf. her hearing aids are of no use to her. she has a Panasonic television, which is about 5 years old. i want to program the closed caption feature of her television, so she can at least read the words as being said on the screen. i have made several attempts to install this feature, but without success. i go to the menu screen and click on cc. nothing happens. need advice on what the heck i am doing wrong. any takers?