As you sign up for the first time, the App will prompt you through the steps needed to successfully complete set up.
However, best first step suggestion, go here and watch the overview and getting started videos. They will help to make the set up and pairing process smoother.
Also, you will find a "Quick Start" guide included in the box with each KATANA Safety Arc. This will walk you step by step through the App set up process including how to pair your Arc to your phone.