I started studying Ktor as an introduction to learning server-side code, due to my familiarity with Kotlin. In order to not pigeonhole myself in the world of Kotlin though, I have since switched to Node.js as my backend language of choice.
Stared off with adding Ktor's dependencies as described in Adding Ktor to an existing Gradle project, highlighted in the init branch.
From there, I implemented a full API for checking and placing orders via Creating HTTP APIs, highlighted in the tutorial branch.
My quick and dirty scratch notes from my studies can be found here.