How to dynamic image button in click event by asp.net?

StringBuilder sb = new StringBuilder();
ImageButton imgBtn = new ImageButton();
imgBtn.ID = "imgBtn";
imgBtn.ImageUrl = "images/bestoffer.gif";
imgBtn.Click += new ImageClickEventHandler(imgBtn_Click);
imgBtn.Attributes.Add("style", "border-width: 0px;");
//this.Form.Controls.AddAt(1, imgBtn);
PlaceHolder1.Controls.Add(imgBtn);
sb.Append(imgBtn);

protected void imgBtn_Click(object sender, ImageClickEventArgs e)
    {
        Session["place"] = "BestOffers";
        Session["location"] = null;
        Response.Redirect("listing.aspx");
    }