I am using the Forum Server plug-in with Atahualpa and the changes I make to the colors of the tables in the CSS do not change the appear on the page.

My forum page is http://exploreallofindia.com/forum/, and the text is on dark gray boxes. There are places where there is white text on a white background too.

How can I make changes to the stylesheet for the Forum and have them visible? I simply want all of the text to be readable. Thanks!

The plugin must have its own stylesheet. You can look through the files in the plugin either in its folder in the plugins folder or in the dashboard, at Plugins/Editor, then Select plugin to edit, and you'll see the list of the files making up the plugin.

You can use Firefox/Firebug to see the CSS IDs of the elements you want to change, as in

 .wpf-table td {
border:1px solid #A9D0F5;

Atahualpa's table CSS might be interfering at some point, and I'll bet Juggledad will have some advice for you there.

looks ok to me, did you make soome changes?

i downloaded the style.css from my forum skin file with dreamweaver, reworked the css and then uploaded it back again.
The atahualpa section for styling tables may have an effect as well on forum server.