You can achive this with manu ways
1->
add a placeholder and put your label at runtime
<asp:placeholder id="PlaceHolder1" runat="server" xmlns:asp="#unknown">
</asp:placeholder>
in CS code
PlaceHolder1.Controls.Add(lbl);
2-> set CSS at runtime
style1
{
position:absolute;
left:100px;
top:150px;
}
in CS code
use
Label1.CssClass = "style1";