Type DocumentApp to tell the computer where the prompt will appear.
Use the autocomplete menu to get the UI and to add an alert.
Type your unique alert message.
Save and run the code.

*NOTICE: THERE IS A KNOWN ISSUE WITH THIS LESSON. When you first open your document in Google Docs, the onOpen popup message is not opening automatically as described in the video. This error is due to changes in the Apps Script programming that is fixed in the final video in this lesson. However, if you manually run the script and the popup message appears, then your code is correct.*