Validating the date of birth and wedding date

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C#

design as follows;

Name             txt_name.Text
Date of birth    textbox(calendarimage)
Mobile Number    txt_mobile.text
Wedding date     textbox(calendar image)
Email            txt_mobile.text

i am validating date of birth and wedding date is not same as current date and not more than the current date.

for that validation code as follows;

DateTime DOB = Convert.ToDateTime(FromDate.SelectedDateValue);
                DateTime TodayDate = DateTime.Today;
                if (DOB.Date >= TodayDate.Date) 
                {
                   Label6.Text = ("selected date is not greater than current date");
                }

                DateTime Weddingday = Convert.ToDateTime(Todate.SelectedDateValue);
                DateTime todaydate1 = DateTime.Today;
                if (Weddingday.Date >= todaydate1.Date) 
                {
   Label6.Text = ("selected date is not greater than currentdate");
                }

INSERT BUTTON CODE AS FOLLOWS;

protected void="" eventargs="" mode="hold" />   {
       Label6.Text = "";

       if (FromDate.SelectedDateValue.ToString() == "")
       {
           Label6.Text = "From date is not selected";
           return;
       }
       if (Todate.SelectedDateValue.ToString() == "")
       {
           Label6.Text = "To date is not selected";
           return;
       }

           Sql ="insert into BirthDayWish values('" + txt_name.Text + "','" + FromDate.SelectedDateValue.ToString() + "','" + txt_mobile.Text + "','" + Todate.SelectedDateValue.ToString() + "','" + txt_Email.Text + "','A')";             
        

            try
           {
               SCon.Error = "";
               SCon.ExecSql(Sql);
               if (SCon.Error.ToString() != "";)
               {
                   Label6.Text = Session["Error";].ToString();
               }
               SCon.Con.Close();
}
       catch (Exception Ex1)
       {
           Response.Write(Ex1);
       }
   }

What I have tried:

in the insert code where i put my validation code for Date of Birth and Wedding Date.

please help me.