You can use them to make brushes or simply as an overlay layer and experiment with your blend modes :) I often use blend modes "overlay" "burn" or "dodge".
In my Calendar below, I have recoloured the text, selected and then overlaid with a pattern from the background of my reef image.
I have made 2 different styles of calendar. ...one with week starting Monday and one with week starting Sunday. The images are 1600 X 2000 at 200 dpi and will fit on A4 or American Letter sized paper. I have successfully printed it out on semi gloss card.