I have a model for my project like that shown in the following diagram. I planned the project using Domain Driven Design and development style is Test Driven Development. And layers are as following.
The project is an MVC based web project. So far, I write tests for started projects before. I have not started a new Project with TDD. So I do not know where I start to write tests. Which layer should be developed first? Where should I start?
Is there anyone developed enterprise projects, can share his/her thoughts and experience?
It is always tricky to get a project off the ground using TDD if you have never done it before, and it is too big a topic to discuss in a Stack Overflow answer.
The best I can recommend is to read Growing Object Oriented Software Guided by Tests - in this book you are taken step by step through getting an application off the ground using TDD, and examples of how you would solve different problems using TDD as the application grows. The application they use as an example in the book is realistic and should help you learn the skills required to get yourself off the ground.