Hi Aditya,
Setting permissions on pages and content to prevent some users but allow others to make modifications is possible but doing it automatically is not.
You will have to write custom code and set it up to fire when new users register. The code would have to 1) create a new role for the new user and place the user in that role, 2) create a new page for the newly registered user, and 2) grant permissions on the new page to the new role.
You can get started by reading information on the User Registered Event Handler here: http://www.mojoportal.com/user-registered-event-handlers.aspx.
HTH,
Joe D.