string conString = System.Configuration.ConfigurationManager.AppSettings["ConnectionString"];
SqlConnection sqlConn = new SqlConnection(conString);
sqlConn.Open();
SqlCommand cmd= new SqlCommand("insert into table_name values('"+TxtName.Text+"','"+TxtAddress.Text+"'',"+TxtEmail.Text+"','"+TxtPassword.Text+"','"+TxtAge.Text+"','"+D1.SelectedItem.Text+"'", sqlConn);
cmd.ExecuteNonQuery();
The above code will help you insert values in the db table.
The above code is just an example , make sure that you make the changes in it as per your requirements.