Add-ons in Google Docs are tools built by third-party developers. You can install add-ons to bring more functionality to Docs, Forms, and Sheets.
- Create a new Google Doc
- Change the file name from 'untitled' to a new name (your name add-ons)
- Select 'Get Add-ons' from the Add-on drop-down menu
- Type in 'Magic Rainbow Unicorns' and click on '+ FREE'