Replace
<asp:UpdatePanel ID="MyUpdatePanel" UpdateMode="Conditional" runat="server">
<ContentTemplate>
<a id="btnSave" runat="server" class="button">submit
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnSave" EventName="ServerClick" />
</Triggers>
</asp:UpdatePanel>
with
<asp:UpdatePanel ID="MyUpdatePanel" UpdateMode="Conditional" runat="server">
<ContentTemplate>
<asp:Button id="btnSave" runat="server" onclick="btnSave_Click" Text="Submit"/>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnSave" />
</Triggers>
</asp:UpdatePanel>
Now write in your code behind
public void btnSave_Click(object sender,EventArgs e)
{
}
I have replace anchor tag with button. Because anchor tag does not fire event on server side. You have to use button. In fact you don't even have to use trigger if you have a button inside update panel.