uploading a new picture on image contol by button

        <asp:Image ID="Image1" runat="server" Style="z-index: 101; left: 105px; position: absolute;

            top: 49px" />

        <asp:FileUpload ID="FileUpload1" runat="server" Style="z-index: 103; left: 102px;

            position: absolute; top: 102px" />
<asp:Button ID="Button1" runat="server" Style="z-index: 100; left: 116px; position: absolute;
            top: 165px" Text="Button" />

 
i want to click on upload, search the file , select it and then when i click on Button the new pic replace the previous pic...
 so what VB code i should make on button so that ne ...