How can i create a module in oxid6.5 and i want to extends some model and classes

I want to develop one module and in that module, I need to enhance some existing things.
I want to extend different controllers and models can you give me one example of how to extend the below things?
oxArticle,oxstart, oxist, oxcategories, oxdetails, oxbasket etc

You probably won’t get an answer to such a general question. The following can be found in the developer documentation: