// 1. Install-Package -Id Microsoft.AspNet.WebApi -Version 4.0.30506 -DependencyVersion HighestMinor

// 2. Update-Package Newtonsoft.Json

// 3. Install-Package -Id Microsoft.AspNet.WebApi.Tracing -Version 4.0.30506  // (it is Optional) 

// 4. Add - App_Start/WebApiConfig.cs
WebApiConfig class
{
    public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    // Uncomment the following line of code to enable query support for actions with an IQueryable or IQueryable<T> return type.
    // To avoid processing unexpected or malicious queries, use the validation settings on QueryableAttribute to validate incoming queries.
    // For more information, visit http://go.microsoft.com/fwlink/?LinkId=279712.
    //config.EnableQuerySupport();
 
    // To disable tracing in your application, please comment out or remove the following line of code
    // For more information, refer to: http://www.asp.net/web-api
    config.EnableSystemDiagnosticsTracing();
}

// 5. Add a Global.asax file and open the Global.asax.cs:
protected void Application_Start()
{
    WebApiConfig.Register(GlobalConfiguration.Configuration);
}

// 6. Add - Controllers/ValuesController.cs:
public class ValuesController : ApiController  // : ApiController !!!
{
    // GET api/values
    public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }
 
    // GET api/values/5
    public string Get(int id)
    {
        return "value-" + id;
    }
 
    // POST api/values
    public void Post([FromBody]string value)
    {
    }
 
    // PUT api/values/5
    public void Put(int id, [FromBody]string value)
    {
    }
 
    // DELETE api/values/5
    public void Delete(int id)
    {
    }
}