How do you let users create there own web page in my page?

Im looking for direction, i want users of my site to be able to edit there own web page, which will be hosted on my site, eg, www.mydomain.com/usersite (note not real link) how do i go about doing this, i want an easy for users to edit while protecting everything that they shouldn't be editing, Kind of like myspace were you can only edit your own, by putting the appropriate HTML in and submitting it. I looked a CMS but the dont see to be alble to do what im looking for, is this right?? is there a CMS out there that can do it for me?? any help would be great!

the easiest way would be o use something like xoops:

http://www.xoops.org/

Key features of XOOPS

- Database-driven
XOOPS uses a relational database (currently MySQL) to store data required for running a web-based content management system.

- Fully Modularized
Modules can be installed/uninstalled/ativated/deactivat... with a click using the XOOPS module administration system.

- Personalization
Registered users can edit their profiles, select site themes, upload custom avatars, and much more!

- User Management
The ability to search for users by various criteria, send email and private messages to users through a template-based messaging system.

- Supported World-wide
XOOPS was created and is maintained by a team of several hard-working volunteers working from all over the world. The XOOPS community has more than dozen official support sites around the world for support of non-English speaking users.

- Multi-byte Language Support
Fully supports multi-byte languages, including Japanese, Simplified and Traditional Chinese, Korean, etc.

- Versatile Group Permissions System
Powerful and user-friendly permissions system which enables administrators to set permissions by group.

- Theme-based skinnable interface
XOOPS is driven by a powerful theme system. Both admins and users can change the look of the entire web site with just a click of a mouse. There are also over 60 themes available for download!!