Pop up a dialog box whenever a button is clicked

Question

In my code behind (.ascx.cs)i have a function which retrieves a certain value
public int getCountValue
{
get { return updateCount; }
}
In my page (.ascx)
I have a save button..Whenever user clicks a save button,a dialog box should appear which should say that "you have updated "updateCount" no. of values.Now My problem is that
1.I am not able to pop up a dialog box whenever user clicks a save button
2.I am not able to retrieve the value of updateCount in the dialogbox(page)
My button is
<asp:imagebutton id="btnSave" runat="server" ImageUrl="images/save.gif" ImageAlign="Bottom" ></asp:imagebutton>