In the Simply Kerrin Zen Cart Template the text, including links, in the sidebars (left and right columns) are set to grey, as shown here. 

To change the colour of the Product Description text:

1. Open the stylesheet.css file located in the /includes/templates/simply_kerrin/css/ directory.
2. At the very end of this file, add in a section of code as follows:

   .sideBoxContent a, .sideBoxContent {
   	color: #FF0000;
   	}

   In this example, I have changed the text colour to Red.

3. Save the modified stylesheet.css file.