To increase the text size all you need to do is click on a radio button located at the top right hand side of the page
Alternatively you could use the inbuilt tools provided with each browser:
Netscape and Mozilla users
To increase text size: from the browser menu, select view > text zoom > larger
To decrease text size: from the browser menu, select view > text zoom > smaller
Internet Explorer users
To increase text size: from the browser menu, select view > text size > larger
To decrease text size: from the browser menu, select view > text size > smaller
Opera users
To increase text size: from the browser menu, select view > zoom > 120%
To decrease text size: from the browser menu, select view > zoom > 80%