It depends upon which browser and computer platform you use:

I use Internet Explorer on a PC.
Click on the View menu in IE and scroll down to Text Size. There you can choose from Largest, Larger, Medium, Smaller and Smallest size settings.

I use Internet Explorer on a Mac.
Click on the View menu in IE and scroll down to Text Zoom. There you can choose to increase the text size to as much as 300% or decrease to as much as 50% of the default setting.

I use Netscape on a PC.
Click on the View menu in Netscape and scroll down to either Increase Font or Decrease Font. Repeat this action to increase or decrease more.

I use Netscape on a Mac.
Click on the View menu in Netscape and scroll down to either Increase Font or Decrease Font. Repeat this action to increase or decrease more.