Hi Carolyn,
Adding some custom text and formatting to the editable parts of the homepage is probably the easiest thing to do. And of course you can always use static pages for more details, etc. See:
If you want something that would be visible on any page where a user may first arrive, you could potentially use the Privacy notification widget for this purpose. Its contents are customizable and it will accept markdown formatting, so you can also link to a static page with more information, for example. See:
Of course, if you have developers and are already using the Privacy widget, then you could always duplicate it. The original commit that added this functionality to the 2.5 release (
here) will show you which files are involved.
Cheers,