Multiple Blogs?

well im hosting my own blog and I was searching around on some sites and I see that some sites let all there users make a blog, how can I let all my users create there own blog?

my site is techtakeover.com and the blog is techtakeover.com/blog
id like to make it so users can have the blog domain either be techtakeover.com/username or username.techtakeover.com