Trying to insert a certain field into a table...i cant wrap my mind around this... what am I missin??

Question

I have a ComboBox (dropdown) that I populate from a Database field containing 3 fields.

Prob_id char(4) indexed by 1
Description_id varchar(25)
Status varchar(6)

 I need to be able to write the Prob_id to a different table upon selecting a Description_id. Right now my code passes both the Prob_id and the Description_id to the app and I can write them both to two separate CB boxes ( I did this to make sure the data was being sent).  

However I dont think this is the right way to do this... I cant figure out how to pass the correct Prob_id that corresponds with the Description_id back to the new table.  My instinct tells me I need to be doing this on Server side with a stored procedure that I cant figure out either or I some type of statement that keeps them together on the app side so I could then just pass the Prob_id into the new table. 

Please help I just cant wrap my mind around this
Thanks

This is the code where it is read in.
BR>private void load_cb()
        {
            myconnection.Open();
            SqlCommand get_open = new SqlCommand("mp_statusopen", myconnection);
            get_open.CommandType = CommandType.StoredProcedure;

            //select from Problem_table * where status='open' ordered by prob_id
            //{alNames.Add(drAuthors.GetValue(0));

            SqlDataReader dr_open = get_open.ExecuteReader();
         
           
            string st_open = null;
            string x = null;//added to handle the prob_id
            while (dr_open.Read())
            {
                x = dr_open.GetValue(0).ToString();
                st_open = dr_open.GetValue(1).ToString();
               //GetValue(insert column number starts with 0)
                Desc_cb.Items.Add(st_open);
                Prob_cb.Items.Add(x);//added to handle the prob_id
                         
            }
            myconnection.Close();

        }


This is the button for adding the data back to the DB

private void Submit_btn_Click(object sender, EventArgs e)
        {
            myconnection.Open();

            SqlCommand Submit_btn = new SqlCommand("mp_submitbtn", myconnection);
            Submit_btn.CommandType = CommandType.StoredProcedure;
           
            Submit_btn.Parameters.AddWithValue("@Description", Desc_cb.Text);
            //Submit_btn.Parameters.AddWithValue("@Prob_id", Prob_cb.Text);
            Submit_btn.Parameters.AddWithValue("@Call",Call_box.Text);
            Submit_btn.Parameters.AddWithValue("@date", DateTime.Now.ToString());

            Submit_btn.ExecuteNonQuery();
            myconnection.Close();
        }
;