How to add "Page.Header.Controls.Add(newStyleSheet);" in c# class Library?

public virtual TBuilder Position(TooltipPosition position)
       {
           HtmlLink newStyleSheet = new HtmlLink();
           newStyleSheet.Href = "css/your.css";
           newStyleSheet.Attributes.Add("type", "text/css");
           newStyleSheet.Attributes.Add("rel", "stylesheet");
           Page.Header.Controls.Add(newStyleSheet);

   //        Page.Header.Controls.Add(
   //new System.Web.UI.LiteralControl("<link rel=\"stylesheet\" type=\"text/css\" href=\"" + ResolveUrl("~/Styles/SomeStyle.css") + "\" />"));
           Component.Position = position;
           return this as TBuilder;
       }

Error	1	An object reference is required for the non-static field, method, or property 'System.Web.UI.Page.Header.get'