Prompt User c#

DialogResult dg = MessageBox.Show("Select Direction \n Yes To convert from Fah to Cel \n No To convert From Cel To Fah","Please Select",MessageBoxButtons.YesNo);

            if (dg == DialogResult.OK) // user selected from fah to cel
                Fah_To_Cel(99);
            else // user selected from cel to fah
                Cel_To_Fah(99);