This video from DJI is worth watching.
The first part you may not need since the Spark has been activated.
At the
2:15 minute mark, Ty discusses the flight simulator.
It's unavailable on Android due to an update a while back, but still works fine on iOs. It's fun to practice without fear of damage. You get to monitor the telemetry, flight path, etc. as you would during a flight and you can see how the RTH button works too.
From that point on he discusses how to link the controller with the Spark, how to link the phone only to the Spark, and
how to reset the Sparks WiFi and password.
This video is worth watching a few times because he covers a lot in a short amount of time.
I hope this is the information you were looking for.
Good luck. ?