“Can anyone tell me how can i install wordpress 2.3.1 on a wordpress.com blog?”
You can’t. WordPress.COM is a hosting service providing free WordPress-powered blogs.
If you’re referring to a self-hosted environment using the WordPress software as provided by WordPress.ORG you need to get those details from your hosting company.
So wordpress.ORG is a blogging program while wordpress.COM is a hosting site?
Then may i know is there any free blog host that is able to use wordpress, excluding blogger (if it can) becoz i tried using blogsavy.com and it says they uses wordpress mu but i really dun understand how do install plugins, which is the domain, username and password when i’m trying to install wordpress?
I am not aware of any free hosts that offer requirements high enough to run WordPress. Most free hosts limit their service to static files, and no databases.
Pay for hosting if you want to run your own WordPress. Or use wordpress.com, and live without installing your own plugins and themes.