This skill can send a signal to App Inventor (http://appinventor.mit.edu/explore/). When App Inventor receives this signal, the "when Alexa.sendsSignal" block will be activated. Connect this block to other blocks in App Inventor to cause them to activate too. For example, connect the "call Player.Start" block to the "when Alexa.sendsSignal" block to have App Inventor play music when you open this skill.
To learn how to create Alexa-enabled apps in App Inventor, see the tutorials section on the App Inventor website (http://appinventor.mit.edu/explore/ai2/tutorials.html).