Blogging site

I want to create a blogging site for a particular community. People should be able to just sign up and create their own unique blog. So, each user has a distinct blog for himself/herself.

I am aware of how to give specific rights to users. What I haven’t the faintest clue about is how to give each user his/her own subdomain.

To be more specific, I want something like wordpressblogs.com / wpblogs.com / blogsome.com.

Any guidance would be greatly appreciated.

TIA.

Subir