How do human body cells work?
Perhaps the best way to start understanding the complexity of cell functions (in general) is to watch a video like this one:
Biology: Cell Structure: [7:21 minutes].
Published on Mar 18, 2015, by Nucleus Medical Media.
After this video (referring to animal and plant cells), one can watch other videos on human cell functions and then ask detail questions on this topic in the google.com search engine.