How to get an Id from a selected item in DropDownList - ASP.NET MVC

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C#

ASP.NET

Hi. I have three tables on my database:

Genre(IdGenre, Genre, Description)
Text(IdText, IdUser, Text)
TextGenre(IdTextGenre, IdText(FK), IdGenre(FK)
)

This third tables is to connect text and genre, because I want the table text to have until 2 genres, and When I search for a genre, automatically it shows the text that are in such genre.

My question is: How do I get an Id from a selected item in dropdownlist? Here is my DropDownList

@Html.DropDownListFor(model => model.IdGenero, ((IEnumerable<AllFiction.Models.Genre>
            )ViewBag.Genres).Select(option => new SelectListItem
            {
            Text = option.Genre,
            Value = option.IdGenre.ToString(),
            Selected = (Model != null) && (Model.IdGenre== option.IdGenre)
            }), "Select a Genre")

And here is my action to create Texts:

[HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult CreateText(Text text)
        {
            if (ModelState.IsValid)
            {
               db.Text.Add(text);
           
 TextGenre tg = new TextGenre();
 
               tg.IdText = text.IdText;
               tg.IdGenre = // Here is where i want to put the id of the selected item of the dropdownlist

               db.SaveChanges();
               return RedirectToAction("Index", "User");
            }
               ViewBag.Genres= db.Genre.ToList();
 
            return View(text);
        }

Anyone know how can I do this? Thanks!