Once you've installed the Automatic Backup for Sheets add-on, you can open and use it from any Google Sheet linked to your Google account.
To launch the add-on, open Google Sheets and access the spreadsheet you want to email. If needed, you can create a new spreadsheet by selecting a blank sheet or choosing one from the template gallery.
With the spreadsheet open, navigate to the Extensions menu, select Automatic Backup for Sheets, and then click Open App from the sub menu to launch the add-on.
After opening the app, click the New Task button to begin drafting your email and setting up the schedule.