LCD 16x2 Menu

Hey,

A year ago I started the challenge to create a kind of Aquarium ( Salt water ) controller. Or at least the basic options. Well, I more or less arrived at my destination. But, I can only view the settings on my display. If i wish to change stuff, I have to encode it in the program itself.
For the moment I would like to create a very simple menu to acces and change settings. Could someone point me in the right direction.
I already found a 'MenuBackend' which seems nice, but this one works with a keybord. I work with 6 buttons. ( yes really basic, not even an LCD keypad, only buttons ) Up, down, left, Right, select and menu.

My intention is to create a simple menu like this for now ( When I understand the coding of a simple menu, I can go bigger )

Main = overview led 1 and 2 ( ON or OFF )
Sub1 = Leds
Sub 11 = LED 1 ( ON / OFF)
Sub 12 = LED 2 (ON / OFF )
Sub2 = Fade
Sub 21 = LED 1 ( ON / OFF )
Sub 22 = LED 2 ( On / OFF )

Or something of this kind. Just for me to understand the coding.,

Thx