So you should create subdomain for every user. For example,

• http://mary.example.com 
• http://kate.example.com 
• http://jeff.example.com

Solutions

• Use Subdomain module
• Use Domain Access module

Subdomain module

The subdomain module joins forces with pathauto to automatically place Drupal site content onto subdomains.

Currently, it supports placing each Organic Group and content *OR* node author and content on its own subdomain.

ORGANIC GROUP MODE (using "Frisbee Team" and "Pizza Lovers" as examples):

• pizza-lovers.example.com
• frisbee-team.example.com

You can also specify a custom subdomain to generate things like:

• groups.example.com/pizza-lovers
• groups.example.com/frisbee-team
• communities.example.com/pizza-lovers
• pizza-lovers-rock.example.com

NODE AUTHOR (using "Mary" "Kate" and "Jeff" as examples):

• mary.example.com
• kate.example.com
• jeff.example.com

or with a custom subdomain rewrite, you can also generate subdomains like:

• writers.example.com/mary
• writers.example.com/jeff
• super-kate.example.com/

RELATED MODULES:

Domain Access: If you wish to share content across multiple domains, you might want to try the Domain Access module. Domain Access provides advanced tools for running a group of affiliated sites from one Drupal installation and a single shared database.

INSTALLATION:
Please see the Readme.txt file for detailed instructions on how to install this module.

NOTE: subdomain requires changes to your web server configuration as well as a small patch to Drupal Core. It’s critical that you understand the implications of those changes and how to reverse them should you need to uninstall subdomain or upgrade to a future version of Drupal Core. See readme.txt.

Domain Access module

The Domain Access project is a suite of modules that provide tools for running a group of affiliated sites from one Drupal installation and a single shared database. The module allows you to share users, content, and configurations across a group of sites such as:

• example.com
• one.example.com
• two.example.com
• my.example.com
• thisexample.com <-- can use any domain string
• example.com:3000 <-- treats non-standard ports as unique

By default, these sites share all tables in your Drupal installation. The Domain Prefix module allows for selective, dynamic table prefixing for advanced users.

The module uses Drupal’s Node Access system to determine what content is available on each site in the network. Unlike other multi-domain modules for Drupal, the Domain Access module determines user access based on the active domain that the user is viewing, rather than which group or site the user belongs to.