As mentioned in my previous post, I discovered a more appropriate way to use the Trinitage decoupage kits. Basically for a 6 x 6 card, you need to make two rectangular boxes.
Cut a a piece of white card measuring 10cm by 12cm.
Make 4 score lines at 2cm intervals along the side of the card that measures 10cm.
Fold your card along the score lines and glue together
Then it is just a case of sticking your cut out images to the side of your rectangular boxes and then attaching the pieces to your card.