Hi, I have a netfirms hosting and i want to install the wordpress mu(multi-user) on it ... but i m not able to do so... please help me with it...
Simplest answer is to have your host help you. Any hosting company worth it's weight in Mt. Dew and Cheetos, should be able to help you just fine.
Have you read through the readme file included with the download? Have you followed all of the steps in there? Where specifically are you getting stuck? A good read if you haven't gotten a copy of it yet: http://wpmututorials.com/basics/installing-wordpressmu-the-e-book/
If you are use shared hosting, you can't install wordpress mu that allowed sub domain. You only can install wpmu with folder only. You need to buy vps hosting.