I have been trying to make a FPS Game like Battlefront 1940 but I don't know how to start it. As well as I don't know how to code a FPS Game. I have tried but I just can't code it fully again. I can code it once. But the code doesn't work for the FPS. I looked at other uncopylocked FPS games but most of them I don't understand what the code means and where everything is suppose to go?

Could someone show me how I should start the main part of the coding and origination parts?