What should I do if the button click does not work?

Question

ASP.NET

I wrote the markup, which is located at Views/Home/Index:

<form asp-controller="Home" asp-action="Index" method="post">
div class="demo-btns">
<div class="info">
<div class="buttons">
<p><input type="text" name="userName" placeholder="Name:" size="18" /></p>
<p><input type="text" name="roomCode" placeholder="Code of the room:" size="18" /></p>
<input type="submit" class="modal__trigger2" value="Join Room" />
</div>
</div>
</div>
</form>

Here is the controller:

public class HomeController : Controller
    {
        [HttpGet]
        public IActionResult Index()
        {
            return View();
        }

        [HttpPost]
        public IActionResult Index(string userName, string roomCode)
        {
            string data = $"Username: {userName}, Roomcode: {roomCode}";
            return Content(data);
        }
    }

I click on the button, but nothing happens. What to do?