- Define the business scenarios that need to be audited.
- Identify the code entry points where those scenarios happen
- Design the audit data model based on what data you want/need to store
- Write data in your audit table/tables on the previously identified code entry points
This answer is intentionally vague. Auditing is not something that ASP.NET or any framework can do for you. This is usually intimately related to your business logic code and requirements
solved How to Implement Audit trial in ASP.NET MVC [closed]