First select new Porject and select MVC4WebAppliction.
For creating API we need to workin only one controller file i.e. ValuesController. I have created single get method for learning puspose First Create Customer Class file under model and refrence to on your controller file
After Implementation of Get Methods you need to execute/test this page, you will found API URi like this...
After success full creation of Web APi now its time to integrate this on your application.
For demo purpose i have created a page in a same project you can implement this on any other sites also.
In my case for Accessing the created API need to create Controller APITestController and View for viewing purpose just like below image
once you created the view page now you need to write some code for accessing the API, for example i am writing here in jQuery like below image