When you go to make your print, you also need to draw the registration marks on your fabric with a removeable pen or chalk. Then line up the registration mark on one screen with the mark on the fabric and make your print. After that is dry, (you can cheat with a hair dryer:-)) repeat with the other screen and the other color of ink.
You can do as many colors as you'd like, and they can overlap if you'd like also. They make transparent ink that you can tint with other colors, I'm still waiting for a chance to experiment more with that, too many ideas! I did use it on this card so it wasn't quite so opaque. I added stitching for the berry tops.