If I understand what you're after correctly, you want to create additional List
definitions.
The yeoman generator creates some default ones for you (User, Post, Enquiry, etc.) but you can create as many of your own as you like by adding more files to that folder.
Each List
you define can have any combination of fields added to it (from the available field types) so you can use them to define any type of data you need.
Keystone's default configuration will automatically import all the .js
files in the ./models
folder, the convention is to define a single List per file. Each list you define gets its own section in the Admin UI so your users can manage their content.
The docs have an example list definition which you can copy here: http://keystonejs.com/docs/database/#lists-example
Hope this points you in the right direction!