Hi ,
Check this
<td runat="server" id="tdColor">
protected void Page_Load(object sender, EventArgs e)
{
tdColor.Style.Add(HtmlTextWriterStyle.BackgroundColor, "Red");
}
<table style="width: 100%;">
<tr>
<td runat="server" id="tdColor">
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
</table>
Best Regards
M.Mitwalli