Online Express is a plug-in that is present in the left navigation menu as its own item. If installed, it will always be present by default for users with Supervisor rights and for the Supervisor user:
Online Express in left navigation menu

If your Raiser's Edge is hosted by Blackbaud:

If your Raiser's Edge is not hosted by Blackbaud:

Online Express must be installed on each workstation that will access it. It is an additional install to The Raiser's Edge and not part of the core Raiser's Edge installation. Log into The Raiser's Edge as a user with Supervisor rights on the workstation: