dependency injection in c# for enterprise application

I have gone through the below links and have got basic idea of what dependency injection is

https://www.codeproject.com/Tips/657668/Dependency-Injection-DI

https://www.c-sharpcorner.com/UploadFile/dacca2/unit-test-using-mock-object-in-dependency-injection/

still I am consufed on how to apply this dependency injection with unit testing for an enterprise application?(ASP.net web application).can some one help me with the examples