As i dont know what broswer you have i will tell you how to make text bigger on IE, Firefox and opera
Firefox
http://www.bbc.co.uk/accessibility/win/seeing/text/browser/firefox2.shtml
Internet Explorer
http://www.bbc.co.uk/accessibility/win/seeing/text/browser/explorer7.shtml
Opera
http://www.bbc.co.uk/accessibility/win/seeing/text/browser/opera9.shtml
Or you can hold down "crtl" and move the mouse wheel backwards and forwards to adjust text size
