As Robert said, either select the Text tool, or press T and you will get an I-beam. Click on your image to start typing, or click and drag in the image to create a text box in which you can type (er…or did dynamic text start with v.6?). The text will be the color of the foreground swatch, by the way, at the bottom of your toolbox (the one in the front). To switch colors prior to setting your text, you can click the eyedropper and select the color you’d like from the color pallete.
(There are many ways to do all of the stuff I said above, but I feel this would be easiest for someone brand-spankin-new to PS.)
P.S.
I’d like to send a thank you to your son-in-law. 🙂