To attach transparencies see the options in 'Working with Vellum'
Transparencies can cause the entire mood of a piece to change when placed over different background papers. Vintage images printed on transparencies appear soft & rather ethereal & when the image is placed over decorative papers, such as text, music or script handwriting the effect is just wonderful.
Keep in mind that all colours & designs of the selected background papers will show through the transparency. Lay the transparency over the top of the papers until you find one that appeals to you.