In this case I did not get to do a complete set up from the ground up as Republic Wireless already set these up and provided an account email and password. But I suspect the set-up is fairly straightforward using their app which you can download at your respective store. The app itself is very easy to navigate and there aren't a ton of settings which is good. When you open the app (after signing in) you will have the home screen shown below. More or less in the center is the Push & Talk button. This allows you to communicate with any of your channels, which can be selected from the bottom where it says "Change Channels." Whichever channel you are on you can then tap the Members icon in the lower left to see who is on that channel. Very intuitive. Selecting the Menu in the top left brings up options to add channels, manage channels, get info on each Relay, and change your settings. Under Settings you have Notification, Audio, as well as a place to add additional Relays. I highly recommend you enable the notifications as it will alert you if someone starts talking on one of your channels.
Selecting your Relay, in this case they named it Eager Unicorn, you can get more information about the device. You can change the name, send diagnostic info, manage channels (now has up to 25), see battery status, cell and Wi-Fi connectivity, and check for updates. But possibly the most important is the location tracker, this is enabled by a slider. For each Relay on your account you can adjust these settings independently.
At the top of this list you can select to add or manage channels. Originally this was limited to 5, but with a recent update they increased this to 25. This should be more than enough, honestly I think 10 would be plenty since it is a little cumbersome to change channels on the Relay. There are some preset options like the daily joke, instant chat, echo, translate, and music; besides your normal Relay chat channels.