Hi,
First remove the runat="server" from the DIV and add a Hidde field with runat="server" on your aspx page like:
<input type="hidden" id="hdHTML" runat="server" />
and now store the InnerHTML in the Hidden field
<script type="text/javascript">
$(document).ready(function () {
$('#btnAssignJudToCourse').click(function () {
$('#hdHTML').val($('#ulAndil').html());
});
});
</script>
now on the cs page get the HTML like
protected void btnAssignJudToCourse_Click(object sender, EventArgs e)
{
string html = this.hdHTML.Value;
}
if you are using Master Page then the IDs for server controls may be different as it start with ContentBody_. please check it and use if you are using master page.
good luck.