popup window asp.net

Hi,
I am using following code for popup control in asp.net 2.0 with c# as code behind.

    protected void Page_Load(object sender, EventArgs e)
    {
         Button1.Attributes.Add("onclick", "window.confirm('You are about to delete a record, would you like to continue ?')");
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
            Response.Redirect("~/TimeTracker/TimeEntry.aspx");
    }
When i click the asp: Button1 the popup window shows but the problem with this is after popup window is displayed clicking ok and cancel both are  taking me to timeentry.aspx page. only ok should take me to the nextpage.aspx.

I need some help on passing values from popup window to the main window.