Or, with the frame selected, simply press Enter to begin entering text.
piano888, how are the YouTube tutorials not what you’re looking for? They seem to be written and produced for just such a purpose as you’re seeking.
In the search field for the online manual, simply type “frames.” Or you can navigate through the table of contents on the left side, which seems to be fairly clearly laid out.
As you said, for everything else, there’s the forum.