Ooh... easy to understand. Not sure about that one. If you're trying to mimic what's in AMH, the meat of what you'll want to look at in the code is in Sub NameEntry. It's obviously been awhile since I've implemented this, so I'm going to forget stuff, but here's a basic list:
In AMH, I used CursorPOS to keep track if we were entering a name, and if we were, what position the cursor was in. It was something like this:
50 = not entering initials; it is set to this when the table loads up, and after the start button is pushed on the third initial to go back to not entering initials
99 = exit flag; after the start button is pushed on the third initial, it gets set to this. AFTER it gets set to 99, the code then calls NameEntry where it looks for the exit flag and if it's set, it sets CursorPOS to 50 (to exit name entry) and exits the NameEntry Sub
0 = Set to this at the end of a game and the player has beaten the high score. Initials are stored in an array, so you can use CursorPOS as the array index, so you need to start with 0.
You need to include in your flipper code a check for whether you're entering initials. In my code, if CusorPOS did NOT equal 50, then run the NameEntry stuff. I personally decided to put my character incrementing/decrementing here (as opposed to a different sub), so you have to do a check if you're near the end of your of the alphabet loop.
You need to include in your start button code a check. In my code, if CusorPOS did NOT equal 50, then you'd either store the current character in the Initials array at position CursorPOS and move the CursorPOS + 1, or you'd move the CursorPOS - 1 and set the Initials array at position CursorPOS to blank (the number 32), OR if it's the third (and last) character then you store the initials.
The meat of the NameEntry sub goes something like this:
First check if the exit flag got set; if it did, reload the high scores (since the new high score got set with the last initial entry), set CursorPOS to 50 (so your flipper and start code don't run any initials code), and exit the sub since you're done
I have 6 checks to determine if you're near the beginning or end of the alphabet loop. These checks could be skipped entirely if you don't want to give the effect of scrolling through the alphabet; if all you want is to display the current character you're on, then you could just something like your DMDScene call and passing in the current character you're one. One simple line.
I don't mind explaining in more detail how I personally implemented it if you want more. I'm not sure if I can make generic enough to give you steps and let you code the specific implementation yourself.