I can empathise with you on this one. Most (if not all) of these devices expect the user to be familiar with the basic operations. I bought one for my wife twelve months ago. There was much frustration in the initial stages - and muttering of words which should not appear in print
. These days she's more or less fully confident in at least the basics of text sending and receiving.
I don't text with my Androids, but my guess is that it's much like any other Andriod data input - tap on the screen where you want the cursor to be and type from there. Stretching the screen out to enlarge the print size may be helpful here. The usual Android keyboard uses a backward facing arrow to delete text behind the cursor when tapped. Dragging text up and down the screen with one finger replaces the scroll functions on keyboard devices.
The was always going to be a book called Android Phones for Dummies -
. Your library might have it; or it may be a worthwhile investment.
Persist, practise, explore, ask. Most of us blundered into becoming familiar and competent with these newer technologies.
Android is just one more of those.