How can I create a Modal window where i cn register a page in javascript?

Step 1: Frist create a div.

<div id="dialog"  style="display: none">
                    <iframe id="showpage" runat="server" height="400" width="650" src=""></iframe>
                </div>
                <asp:HiddenField ID="hdnPopUp" runat="server" />
    </div>

Step 2: Create a Java script function

function showDialog() {
          $(function () {
              // Dialog
              $('#dialog').dialog({
                  modal: true,
                  //autoOpen: false,
                  width: 650,
                  hight: 400,
                  close: function (event, ui) {
                      $('#dialog').hide(); document.getElementById('<%=BtnGo.ClientID%>').click();
                      //parent.location.href = parent.location.href;
                  },
                  open: function (event, ui) {
                      $('#dialog').show();
                      $(this).parent().children().children('.ui-dialog-titlebar-close').hide();
                  },
                  buttons: [{
                      text: "close",
                      click: function () {
                          $(this).dialog("close");
                      }
                  }
                  ]

              });
              // Dialog Link
          });
          }

Step 3: Here Hidden field work as a Flag.
set the flag/hidden field value as 0 in Page load event.

if (!string.IsNullOrEmpty(hdnPopUp.Value) && hdnPopUp.Value.Equals("1"))
            {
                hdnPopUp.Value = "0";
            }

Step 4: register the page and set the hidden field value 1. means set the status value as 1.

String csname2 = "ViewPopUp";
           System.Type cstype2 = this.GetType();
           ClientScriptManager cs2 = this.ClientScript;
           if (!cs2.IsStartupScriptRegistered(cstype2, csname2))
           {
               String cstext2 = "showDialog();";
               showPrintpage.Attributes.Remove("src");
               showPrintpage.Attributes.Add("src", "About.aspx?id=" + 1);
               cs2.RegisterStartupScript(cstype2, csname2, cstext2, true);
               hdnPopUp.Value = "1";

           }