PDFsharp & MigraDoc Foundation

            PdfDocument document = new PdfDocument();

            // Create a new page
            PdfPage page = document.AddPage();
            page.Size = PageSize.Letter;
            page.Orientation = PageOrientation.Portrait;
           
            XGraphics gfx = XGraphics.FromPdfPage(page, XPageDirection.Downwards);

            // Draw background
            gfx.DrawImage(XImage.FromFile("Background.pdf"), 0, 0);

            // Write on top of background with known colors
            gfx.DrawString("Name", new XFont("Garamond", 12, XFontStyle.Regular), XBrushes.Firebrick, 100, 670, XStringFormats.TopLeft);
            gfx.DrawString("Title", new XFont("Garamond", 10, XFontStyle.Italic), XBrushes.DodgerBlue, 100, 685, XStringFormats.TopLeft);
           
            // Write on top of background with custom colors
            // DOES NOT WORK, COMES OUT BLACK!!!!!!

            gfx.DrawString("Phone", new XFont("Garamond", 12, XFontStyle.Regular), new XSolidBrush(XColor.FromCmyk(62, 28, 2, 3)), 100, 700, XStringFormats.TopLeft);
            gfx.DrawString("Email", new XFont("Garamond", 10, XFontStyle.Regular), new XSolidBrush(XColor.FromCmyk(5, 95, 39, 16)), 100, 715, XStringFormats.TopLeft);

            // Save the document...
            document.Save("BackgroundWithText.pdf");