Access method of a webservice.svc from jquery

I have a WebServiceto which I want to access its methods, I have searched but I have not found a solution on how to attack the service, I .svconly find services .asmx.

From c# I add the service reference and to use the method I do the following:

ServicioClient SClient = new ServicioClient();
Gestores_SesionResponse sesionRespuesta = null;
Gestores_SesionRequest datosSesion = new Gestores_SesionRequest(){
  Pwd = model.Password,
  UserName = model.UserName
};
SClient.dbGestores_Sesion(datosSesion, out sesionRespuesta);

But I want to attack the same service from jquery , I have tried as follows:

$.ajax({ 
  url: 'http://nombredominio.com.mx:1234/Service.svc/dbGestores_Sesion',
  data: '{"UserName":"usuario","Pwd":"123456"}',
  contentType: 'application/json; charset=utf-8',
  method: 'post',
  dataType: 'json',
  processdata: true,
  success: function (data) {
    console.log("exito");
    console.log(data);
  },
  error: function (result) {
    console.log("error");
    console.log(result);
  }
});

But when making the request it sends meerror 400

XMLHttpRequest cannot load http://domainname.com.mc:1234/service.svc/dbGestores_Session . Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin ' http://localhost:50478 ' is therefore not allowed access. The response had HTTP status code 400.

Where dbGestores_Sessionis the name of the method, and receives 2 username and password parameters, so how can I access my method WebService.svcfrom jquery ? And how can I get the data from the outone I use in c# with jquery ?

Note: If I access http://domainname.com.mc:1234/service.svc it shows me the service page but if I access this way http://domainname.com.mc:1234/service.svc/dbGestores_Session only show a blank page