Once you want to get any more complex stuff going, you'll need a helper library to manage stuff like the internal temperature sensor, LED matrix, or Bluetooth connection.

To make your life easier, we've written up a wrapper library that manages all this stuff for you.

You'll also need to install some helpers.

Open up the Arduino library manager:

Search for the BLEPeripheral library and install it

Search for the Adafruit GFX library and install it

If using an earlier version of the Arduino IDE (prior to 1.8.10), also locate and install Adafruit_BusIO (newer versions will install this dependency automatically).

Search for the Adafruit Microbit library and install it

We also have a great tutorial on Arduino library installation at:
http://learn.adafruit.com/adafruit-all-about-arduino-libraries-install-use

Once you've re-started the Arduino IDE you should see the library examples appear in the File->Examples->Adafruit_Microbit menu