I need to increase the font size of the display. It is about 8 point. I cannot find an article that says how to increase the display when I first open Thunderbird. I can increase the font form the actual message or replies.

If you're talking about the size of things like the message list, Folders List, etc., check out the menu options <View | Font Size> (if the menu bar is hidden, press <Alt> or <F10> to reveal it.)

The message viewing fonts can be changed on the fly with the common Windows keyboard shortcuts <Alt+Plus> to enlarge, <Alt+Minus> to shrink, and <Alt+0> to reset.