Annotation how to create DT3

I rarely annotate my pdfs, preferring to bookmark word/words of interest. Experimenting with DT3, i have highlighted some content in a pdf and note that a list of highlighted content appears in the inspector and as a separate file in a new folder annotation But how do I create an annotation - I have looked in help but cannot find the answer - so that the items is displayed in the annotate box in the inspector? Also why does the box give the impression of only being able to accommodate 1 annotation per pdf? Sorry if all that sounds like I di not know what I am doing, i don’t.

Highlighted content appears in the Document Inspector > Annotations. Details added to a selected annotation. Those details are visible in this inspector and if you double-click the annotation in the PDF.

Those are not the same thing as an Annotation file shown in the Annotations & Reminders Inspector. Those Annotation files are separate files, added to an Annotations group in the root of the database.
You can create one by clicking the down arrow next to the Annotations label above the text field, or by merely typing into the text field. And yes, only one Annotation file is connected to a source file.

Thank you.
Whereabouts is the Annotations label above the text field?

It might be a good idea to use a different terminology for these two features. If it’s only highlighted text that appears in the Document Annotations inspector, why not call it Highlights?

If it’s only highlighted text that appears in the Document Annotations inspector, why not call it Highlights?

It’s not. There other other Annotation types as well.