You can increase or decrease the size of the text on a page to page basis by using the facility at the top of each webpage in this site. You can also select one of four background and font colour combination buttons (this also on a page to page basis).
For an overall change in text size see below:
Internet Explorer
View / Text Size
Netscape Navigator
Edit / Preferences / Appearance / Fonts
Opera
File / Preferences / Fonts / Minimum font size
Firefox
View / Text Size / increase or decrease
Alternatively, in Internet Explorer and Mozilla Firefox, if you have a mouse with a wheel, hold down the CTRL key on your keyboard whilst moving the wheel forward, to increase text size, or backward, to reduce text size.