It is designed to be simple to include into any website that is built using Vapor using just the Vapor Provider. It can be added to a path in a site or can even be used as the main site itself.
There is an example site on Github that demonstrates how to integrate SteamPress into a site, including all the Leaf templates and how to use them. It is a good starting place to clone and get up and running quickly. This site is actually the example site deployed!