where to check the state of dynamically created checkboxes - asp.net

Question

Hello in my programme I need to create dynamically checkboxlist with items - got from teh database.
The problem is when Clicking a button i should get the text from cn only checked checkboxes and I should redirect the user to another page
And I have difficulty with determining width of the controls are checkedore
if I checked immediately after they are added
So if I write
if (mycheckbox.Items[s].Selected==true)
after this line
Page.FindControl("form1").Controls.Add(mycheckbox);
they are not checked still so this will be always false)
On postback event (clicking the button ) - we know on postback event dynamic controls no longer exist)
here is my code
protected void ddlNumberTourists_SelectedIndexChanged(object sender, EventArgs e)
{
int numTourists = Convert.ToInt32(ddlNumberTourists.SelectedItem.Text);
for (int i = 0; i < numTourists; i++)
{
string connectionString = "Server=localhost\\SQLEXPRESS;Database=excursion;Trusted_Connection=true";
string query =
"SELECT Extra_Charge_ID, Excursion_ID, Amout, Extra_Charge_Description FROM EXTRA_CHARGES WHERE Excursion_ID=" + mynewstring;
SqlConnection conn = new SqlConnection(connectionString);
SqlCommand cmd = new SqlCommand(query, conn);
try
{
conn.Open();
SqlDataReader rd = cmd.ExecuteReader();
int s = 0;
while (rd.Read())
{
mycheckbox.ID = "chkblextracharge" + i.ToString() + s.ToString();
mycheckbox.Items.Add(rd["Extra_Charge_Description"].ToString());
Page.FindControl("form1").Controls.Add(mycheckbox);
s++;
}
}//End of try
catch (Exception ex)
{ }
}//end of for

Answer 1

I've implemented a client-side check using jQuery in my online Quiz engine (demo: http://webinfocentral.com): the extract from that code snippet follows:
var _rows = $(this).find('tr');
for (i = 0; i < _rows.length; i++) {
// find out if checkbox is checked
_checked = $(_rows[i]).find('input:checkbox').is(':checked');
}

Answer 2

conn.Open();
SqlDataReader rd = cmd.ExecuteReader();
int s = 0;
mycheckboxList = new CheckBoxList();
mycheckboxList.ID = "chkblextracharge" + i.ToString();
while (rd.Read())
{
ListItem LI = new ListItem(rd["Extra_Charge_Description"].ToString(), s.ToString());
LI.Selected = rd["Selected_Criteria"] == "TRUE";
mycheckboxList.Items.Add(LI);
s++;
}
Page.FindControl("form1").Controls.Add(mycheckboxList);