Need to create parameterized constructor in webAPI

Question

I need some sample example with parameterized constructor using reprository and web-API

 

I tried this:

public class TestUserController : ApiController
{

private readonly IUserRepository  UserRepository;

public TestUsersController()
{

}
public TestUsersController(IUserRepository  UserRepository)
{
this.UserRepository = UserRepository;.........this parameterized constructor is not hitting and getting always null
}