how to not display button on page load time in asp.net .

Question

Hi frnds

how to none display button on page load time in asp.net .

i have a page treeview with submit button.

here i want when page will load that time button should not be dispaly and once i select on tree view that time button should be enable

i am sharing my code

<div id="CheckBoxList1">

<asp:Label ID="lbl" runat="server" Text="Department to send "></asp:Label>

<br />

<asp:TreeView ID="TreeView1" runat="server" ShowCheckBoxes="All"></asp:TreeView>

</div>

<asp:Button ID="btnSubmit" runat="server" Text="Send" CssClass="btn btn-primary" ToolTip="Click To Send"/>