I am looking for a simple compiler that compiles a simple language, I need it to write a paper about it and to learn how compilers work, I am not looking for a sophisticated thi
You should read a book on compiler design; it should have the theory you want to know, as well as some appropriately simple examples.
I recommend "the dragon book": Principles of Compiler Design, by Aho and Ullman. It has been many years since I read it, so I don't recall exactly what examples are available, but it is a very good text.