WPMS multisite domain root?

Hi, I’d like to convert an existing site to a WPMS network, adding localised sites in this format: mydomain.com/city1 and mydomain.com/city2
What should I type into the fields in the plugin’s dashboard?
the fields are:
Domain: (should this include the https:// )
Root Path: (would this be the domain + the /localised name?)
Site ID: (should I have a hidden site which uses the root domain as ‘ID0’)
Current Blog ID: ?
Primary Network ID: ?

Thanks in advance for help.