To implement the Microsoft Graph API beta in an ASP.NET Core application, you can follow these steps:

1. Install the Microsoft.Graph.Beta package from NuGet.
2. Create a new controller that will expose the Graph API endpoints.
3. In the controller, create a method that calls the Graph API endpoint.
4. Use the Microsoft.Graph.Beta.GraphServiceClient class to create a client for the Graph API.
5. Use the GraphServiceClient class to call the desired endpoint.
6. Return the results of the call from the method.

Here is an example of how to implement the Microsoft Graph API beta in an ASP.NET Core application:

C#

using Microsoft.Graph.Beta;
using Microsoft.AspNetCore.Mvc;

namespace MyApp.Controllers
{
    public class GraphApiController : Controller
    {
        public async Task<IActionResult> GetMe()
        {
            // Create a client for the Graph API.
            var client = new GraphServiceClient();

            // Call the "me" endpoint.
            var me = await client.Me.Request().GetAsync();

            // Return the results of the call.
            return Ok(me);
        }
    }
}

In this example, we first create a controller named GraphApiController. The class GraphApiController has a method called GetMe(). The GetMe() method calls the Graph API endpoint “me” and returns the result of the call.

The GetMe() method first creates a client for the Graph API using the GraphServiceClient class. This method then calls the Me.Request().GetAsync() method to call the "me" endpoint. Finally, the method returns the results of the call.