public JsonResult GetData(string param1, string param2)
    {
        List<YourModecClass> data = new List<YourlModelClass>();

            //Mockup data only...you should get the data from DB source
            data = new List<YourModelClass>();
            data.Add(new YourModelClass() { Region = "", Value_TY = 0});
            data.Add(new YourModelClass() { Region = "", Value_TY = 0 });
        return Json(data, JsonRequestBehavior.AllowGet);
     }

function getServerData() {
var entity = {
    param1: param1 //--> ths is a variable
    param2: "value" //--> hardcoded
}
var parameter = JSON.stringify(entity);

$.ajax({
    type: "POST",
    url: url + "/GetData",
    data: parameter,
    dataType: "json",
    contentType: "application/json",
    async: true,
    beforeSend: function () {
    },
    success: function (response, status, xhr) {
        yourJavascriptVariable = response;
        doSomethingWithreceivedDataAbove();
    },
    error: function (xhr, status, error) {
        debugger;
    }
});