Need Help For Building algorithm

Dear all.

I am using Below circuit for interfacing Lcd and keypad.
LCD & Keypad Shield Quickstart Guide | Freetronics.
Basically i completed above code and seems working fine. Now plan to build algorithms such that i configure data like date , time, latitude, longitude . after Modifying Display Date and time On screen with Desired angle calculation. Desired angle might Refer to motor Encoder output0-5v converted 0-360 degree.Now i Need Suggestion On Building the code. The Algorithms Steps. I can modify @ any instant. If change time Desired angle has to change accordingly. After changing It show date and time with angle Desired position.

I wanted To manage menus:

i have 4 parameters like:
latitude
longitude
date
time
I have 16x2 lcd and Arduino board. Can some one share me How to manage menus. Can some share me simple code to getting started.Once value set CLock has to display and Perimeter like Postion of motor has to displayed.

Is there any liberay available

http://forum.arduino.cc/index.php?topic=104762.15