Well C like any real programing language has pointers and struts provide much of the framework for member variables so your 90% their. rothn you should try to learn about object oriented design as its a major focus of how the game written. I'd recommend you brush up on C++ and OOD as you grok the SDK, use code blocks to compile if your don't have an IDE and or compiler, Kael's guide is excellent and will get you going in no time. Start off by learning how to do a new xml tag from top to bottom, putting a new tag in the schema, read it into the game and effect some change in the code with it and lastly let the player see the effect by listing it ware appropriate in the Pedia. Then its a matter of designing and implementing useful new things into the code.