how is multisite supposed to work?

I am new to the network site software. Can someone direct me to a basic info page that explains how this all should work?

I have a website and wanted to add a section on it that allows people to create their own blogs. The blogs should have nothing to do with my main website in terms of design and content, and will have their own main page with directions/info on that feature along with a dynamic list of latest blogs, and latest blog posts. How can I do this? I am confused on how to integrate the multi blogs into an existing site.

Thanks!