Those kind of websites that you want to make needs expert knowledge.
Here's my suggestion and it's the closest one you can do:
BuddyPress. Using BuddyPress can let your users make
their own blog and let them post there own things in their blog.
Here's a successful site that uses BuddyPress for their users:
http://xatblogs.com/
It would take months of work if you want
a lot of people to be joining your site. Also, you need to decide on what you would make a website for.