我找到很好的答案在这里Adding动态新VS 2013的UserManager身份角色

I found good answer here Adding Role dynamically in new VS 2013 Identity UserManager

但在情况下提供一个例子，所以你可以检查我要去份额一些默认的code。

But in case to provide an example so you can check it I am gonna share some default code.

首先确保你已经插入的角色。

First make sure you have Roles inserted.

和第二个测试用户的注册方法。

And second test it on user register method.

[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Register(RegisterViewModel model)
{
    if (ModelState.IsValid)
    {
        var user = new ApplicationUser() { UserName = model.UserName  };

        var result = await UserManager.CreateAsync(user, model.Password);
        if (result.Succeeded)
        {
            var currentUser = UserManager.FindByName(user.UserName); 

            var roleresult = UserManager.AddToRole(currentUser.Id, "Superusers");

            await SignInAsync(user, isPersistent: false);
            return RedirectToAction("Index", "Home");
        }
        else
        {
            AddErrors(result);
        }
    }

    // If we got this far, something failed, redisplay form
    return View(model);
}

最后，你必须从角色下拉列表弄好了。

And finally you have to get "Superusers" from the Roles Dropdown List somehow.