How to reference a web service with a login form?

Question

I have a username and password in an existing web service, and I want to use the username and password that I have in a method called Login().

I have the followings records:

APIApp.cs

namespace App.Work.API
{
    public class APIApp : IAPIApp
    {
               
        private readonly LogInServiceClient _loginService;
    
        public APIApp()
        {
            String url = @"http://(An IP)";
            BasicHttpBinding binding = new BasicHttpBinding();
           
            this._loginService = new LogInServiceClient(binding, new EndpointAddress(url + "/Services/LogInService.svc"));
    
        }

        // Invocando Login

        public void Login()
        {            
            using (OperationContextScope scope = new OperationContextScope(_loginService.InnerChannel))
            {
                // Pasar los parametros por cabecera.
                // Setting the headers
                 var request  = new HttpRequestMessageProperty();              
              
                request .Headers["Language"] = Language;
                request .Headers["ModuleId"] = ModuleId.ToString(CultureInfo.CurrentCulture);
                            
                OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = request ;
               
                LogInInfoDTO loginInfo = _loginService.AreUserAndPasswordCorrect("(An username)", "(A password)", Extension);

                if (loginInfo.Authenticated)
                {

                (I don't know if I must to put anything there.)

                   
                   
                }

            }
        }

}

}

IAPIApp.cs

namespace APP.Work.API
{
    public interface IAPIResuPlus
    { 
        void Login();
        void ObtenerTrabajadores();
    }
}

A controller:

    using APP.Work.Services.LogInService;
using Microsoft.AspNetCore.Mvc;

namespace APP.Work.View;

[Route("api/[controller]")]
[ApiController]
public class APIAPPController : ControllerBase
{
    IAPIApp _api;
    public APIAPPController(IAPIApp api)
    {
        this._api = api;
    }

    [HttpGet("[action]")]
    public IActionResult Login()
    {
        _api.Login();

        return Ok();
    }

}

The view:

I'm sorry if I didn't put the code correctly, but since I'm new to using apis, I'm also new to this forum xD thanks for your help!