Login page in mvc pattern

You would do something along these lines

Assuming your page was shown from a call to an action method named Logon, you could code another Logon action method that is limited to HttpPost

[HttpPost]
public ActionResult LogOn(LogOnModel model)
{
    if (ModelState.IsValid)
    {
        if (MembershipService.ValidateUser(model.UserName, model.Password))
        {
            AuthenticationService.SignIn(model.UserName, model.RememberMe);
            return RedirectToAction("Index", "Home");
        }
        else
        {
            ModelState.AddModelError("", "The user name or password provided is incorrect.");
        }
    }
    // If we got this far, something failed - redisplay form with model
    return View(model);
}

The code for LogOnModel would be something like this...

public class LogOnModel
{
    [Required]
    [DisplayName("User name")]
    public string UserName { get; set; }

    [Required]
    [DataType(DataType.Password)]
    [DisplayName("Password")]
    public string Password { get; set; }

    [DisplayName("Remember me?")]
    public bool RememberMe { get; set; }
}

This example is using the membership service to check for the user, but you could easily roll your own here if you wanted