Setting up a WP multisite

Hi,

I am new with setting up a multisite. I want to create a multisite using subdirectories for a blog with every city on a subfolder (like: mydomain.com/paris, mydomain.com/newyork) etc. I have hosting with 10 databases but I have no idea how to use this best. Does any one have any recommendations before I start? Do I have to set up every city-blog on a different database? Is it possible to add a new subfolder later on?

Tips and keywords to google tutorials are welcome :)!