I recommend you to go through the datasheet of the graphical lcd first. Learn how the display is arranged into pages and all. Then try to find out how to initialize the display. Then learn how to turn on a single pixel on the screen. After that try to make a charater map for alphanumeric character to be displayed. Try to make the seperate code for all the above steps yourself. At this stage only if you have troubles search for someone else’s code.