Adding the CANONICAL tag to my page for SEO through code behind?

This is what i had to do..................

    Dim seoTag As HtmlLink = New HtmlLink()
    seoTag.Attributes.Add("rel", "canonical")
    seoTag.Href = "http://www.erate.co.za/"
    Header.Controls.Add(seoTag)

More information Here

Why not create your canonical element as a server control:

<link rel="canonical" href="" runat="server" id="canonical"/>

Then manipulate the canonical object in your page (or master page) class. Generic tags are treated as instances of HtmlGenericControl which allows one to set arbitrary attributes:

canonical.Attributes["href"] = whatever;