Combobox begginger question

[Jeff Williams]

I have the code below to fill a combobox. I would appreciate any
comments on a better way to do this fill.

My may problem is how do I set the selected combo box display value
based on the "Id" column and a value of "paytype". Also once the user
selects a combobox item from the dropdown how do I then retrieve the
"paytype" value.

void Fill_LookupType()
{
int nItem;
nItem = 0;

string select = "SELECT description, lookuptypevalue ";
select += "FROM lookuptypes ";
select += "WHERE active = 1 ";
select += "ORDER BY description ASC ";
dbConnect Connection = new dbConnect();
OdbcConnection conn = new OdbcConnection( @Connection.Connect());
conn.Open();
OdbcCommand cmd = new OdbcCommand(select,conn);
OdbcDataReader aReader = cmd.ExecuteReader();

DataTable list = new DataTable();
list.Columns.Add(new DataColumn("Display", typeof(string)));
list.Columns.Add(new DataColumn("Id", typeof(string)));

while(aReader.Read())
{
list.Rows.Add(list.NewRow());
list.Rows[nItem][0] = aReader.GetString(0);
list.Rows[nItem++][1] = aReader.GetString(1);
}

aReader.Close();
conn.Close();

this.cb_LookupType.DataSource = list;
this.cb_LookupType.DisplayMember = "Display";
this.cb_LookupType.ValueMember = "Id";
;

}