Error message position in mvc razor - asp.net-mvc

Question

I'm trying to put custom error messages for a login and registration forms.
So far I have the form to check if there's an email already registered, if it is, it will return
Response.Write("There's already someone with that email")
But the problem with this is that the message will only appear on the top of the website.
Is there a way I could display these error messages somewhere else?
I know that in the model I could just put
[Required(ErrorMessage = "Something here")]
And then just put in the view somewhere
#Html.ValidationMessageFor(a =>a.Email)
and it will display the error there.
The code that I have for now is this:
[HttpPost]
public ActionResult Register(Registration signingUp)
{
var db = new ShareRideDBEntities();
if (ModelState.IsValid)
{
//find if email is already signed up
var FindEmail = db.tblProfiles.FirstOrDefault(e => e.PROF_Email == signingUp.Email);
//if email is not found up do this
if (FindEmail == null)
{
var Data = db.tblProfiles.Create();
Data.PROF_Password = signingUp.Password;
Data.PROF_Email = signingUp.Email;
db.tblProfiles.Add(Data);
int Saved = db.SaveChanges();
if (Saved != 0)
{
Response.Write("Registration Successful.");
}
else
{
Response.Write("There was an error.");
}
}
else
{
Response.Write("There's already an user with that email.");
return View();
}
}
else
{
Response.Write("Fill all the fields to continue.");
}
return View();
Now if I do this with an existing email it will return "There's already an user with that email." but it will be display on the top of the website.
How can I make this error message be displayed somewhere else?
I heard something with #Html.Raw() but I'm confused on how to use it.

Answer 1

Using this.ModelState.AddModelError method you can add any custom error message you want. If you specify property name as a key - it will be displayed by corresponding ValidationMessageFor. So in controller instead of writing to response directly do this:
ModelState.AddModelError("Email", "There's already an user with that email.");
return View();
And in view this line which you already have:
#Html.ValidationMessageFor(a =>a.Email)
will display this messagea at whatever part of the page you place it (presumably near the field for email).