Call Controller Action on DropDownList Change in ASP.Net MVC

Hello,

I want to search with dropdownlist in asp.net mvc, but I cannot do it, how can I do it?

@Html.DropDownList("GRUP", (List<SelectListItem>)ViewBag.grup, "", new { })
<button class="btn btn-secondary">Ara</button> 

       public ActionResult Urunler(int? id, int? kimlik)
       {
           var ad = (string)Session["FIRMAKODU"];
           ViewBag.firma = ad;
           var plasiyerid = (string)Session["PLASIYERID"];
           ViewBag.plasiyer = plasiyerid;
           ViewBag.cariid = id;
           ViewBag.fisid = kimlik;
           List<SelectListItem> grup = (from x in db.WEBSTOK
                                       group x by x.GRUP into g
                                       select new SelectListItem
                                       {

                                           Text = g.Key,
                                           Value = g.Key.ToString()
                                       }).ToList();
           ViewBag.grup = grup;
           var stok = db.WEBSTOK.Where(x => x.FIRMA == ad & x.PLASIYER == plasiyerid).ToList();
           return View(stok);
       }