If you are with 2.0, look at the class HtmlMeta. Here is the example from
the msdn:
protected void Page_Load(object sender, EventArgs e)
{
// Create two instances of an HtmlMeta control.
HtmlMeta hm1 = new HtmlMeta();
HtmlMeta hm2 = new HtmlMeta();
// Get a reference to the page header element.
HtmlHead head = (HtmlHead)Page.Header;
// Define an HTML <meta> element that is useful for search engines.
hm1.Name = "keywords";
hm1.Content = "words that describe your web page";
head.Controls.Add(hm1);
// Define an HTML <meta> element with a Scheme attribute.
hm2.Name = "date";
hm2.Content = DateTime.Now.ToString("yyyy-MM-dd");
hm2.Scheme = "YYYY-MM-DD";
head.Controls.Add(hm2);
}