First consider which site collection you would like to add the Masthead Installer to. Whoever has permission to edit that site collection will also be able to enable/disable Masthead Navigation on various sites. If you would like, you can create another site collection specifically for the Masthead Installer so you can easily keep track of who has permission.
To add the Masthead Installer to SharePoint, you can follow the instructions here, or use the instructions below:
- Once you have chosen your initial site where you would like to add the installer, go to Settings and then click Add an app.
- On the Your Apps page, click From Your Organization.
- Click on Masthead Installer, and click Add it. (Note that the installer is free, however you do require a subscription to use Masthead.)
- When you’re asked if you want to trust the app, you can review the Terms & Conditions and Privacy Statement, and then click Trust It.
- The Masthead Installer will now appear on the Site Contents Page. You can navigate to the installer by clicking it on the Site Contents Page.