Don't login to your Joomla! admin panel.
Go to your main hosting account, wherever that may be, and enter your Joomla! template's folder. Go to the template in question: the one whose font color you want to change (or many other attributes pertaining to color, size, etc).
Enter the CSS directory of the target template folder. The target cascading sheet file, the one you'll have to change, will likely be named template.css.
Change the font color there. If you don't have much experience working with code, you'll likely mess things up.
