AoA,
For help on writing and reading Urdu in your webbrowser on basically any operating system, please consult the URDU TEXT HELP pages at:
http://www.geocities.com/urdutext/
To write in Urdu, you have to enable the Urdu keyboard on your operating system.
The problem with the Google Groups is that it specifies Arial fonts which on older windows installations cannot display Urdu. There are several solutions:
1) On either IE or FireFox (on any OS), you can force the fonts to any desired fonts,. e.g. Tahoma, "Arial Unicode MS", or even "Nafees Web Naskh" The procedure for forcing the fonts is given at:
http://www.geocities.com/urdutext/
2) If you are on Windows XP, you can update to the latest Arial fonts which are Urdu-capable (these are part of service pack 2 or something).
If you encounter any problems, please post the details here.