How to remove injection pump and refit another one

Question

Please I need a comprehensive step-by-step guide (for novices) on how to remove and replace the diesel injection pump. Please I know nothing on this, and I would like this info to guide the repair mechanic. Kindly, if possible, post pictures too for a clearer explanation. Also, what is the difference between injection pump and injector? Is it the injector that is programmed of the injection pump? Thank you so much for your help.