inside grid view check box checked row get id of row c#

hi frnds i have a grid view inside get value from database

in add check box inside grid view

i want when check box checked open popup and add some field

i add this process but i can't get right row id please help me i use this program

Center" HeaderStyle-Width="10%"

Visible="false">

server" Text='<%#Eval("Work_Id") %>' Visible="false">

Client Name" ItemStyle-HorizontalAlign="Center" HeaderStyle-Width="10%">

server" Text='<%#Eval("Company_name") %>'>

10%">

Middle" />

on check chenged

protected void CheckedChanged(object sender, EventArgs e)

{

if (sender != null)

{

if (((CheckBox)sender).Checked)

{

txtCompany.Text = string.Empty;

txt_fee.Text = string.Empty;

popup.Show();

}

else

{

popup.Hide();

}

save button:

protected void btn_save(object sender, EventArgs e)

{

Label lbl_pro_id = (Label)grid_data.Rows[0].FindControl("lbl_wokid");

objadmin.Work_Id = int.Parse(lbl_pro_id.Text);

objadmin.ClientId = 0;

objadmin.EpId = 0;

objadmin.Feedback = txtCompany.Text;

if (txt_fee.Text == "")

{

objadmin.Fee = 0;

}

else

{

objadmin.Fee = Convert.ToDecimal(txt_fee.Text);

}

objadmin.end_date = System.DateTime.Now;

DataSet ds = objadmin.binddprt1("updatedescription");

bind();

ScriptManager.RegisterStartupScript(this, GetType(), "alertMessage", "alert('Feedback Save successfully !!');", true);

}