You can try any menu-related sample examples here:
The rotary encoder acts as up/down/enter. So any menu is going to work the same way without the arduino knowing there is a rotary encoder instead of buttons. It's super cool to use a rotary encoder in menu selection. The other 5 buttons are acting as left/right/escape/'1'/'2'. Hook up these keys if you want them.
Essentially, send this to the panel:
"\eFDemo menu\nDisplay\nKeys\nMulti-tap\nBuzzer\nMenu\nLong message\nLEDs\nBacklight\nPassword\nCredits\n~"
If you trim the longest menu item shorter, the menu will automatically become 2 columns, or even more if items are very short.
Hook the panel to your pc with a USB TTL adapter and see what comes out of the panel by turning and pressing buttons.
If you want to enter number with the encoder, send this "\eD3Enter number~". The 3 indicates up to 3 digits, and the rest of the text is a prompt that you can change to anything, like "\eD3Delay(ms)~". The return is sent to serial port in the format of 123~. So if you need a number on arduino, just use my enter number sample code and change the terminator from \n to ~
if (in_char=='\n') INTO if (in_char*=='~')*
You can also whip up your own number entry by writing code on arduino if you are not happy with this number entry, but that will take some time, although much less than dealing with the hardware directly.