Here is the pattern that I used to create my card;

You need to create a card blank measuring 28.4cm x 9.8cm. (this is the longest card that can be created on an A4 sheet because it comprises of 3 EQUAL squares)

Working across the longest edge (ie. top and bottom) and taking each measurement from the last mark made, measure 4.9cm, another 4.9cm, 9.8cm, 4.9cm and a final 4.9cm. Score all of these lines. Mark out the angle lines (shown in green) and score these lines as well.

All of the red lines should be folded inwards (valley folds) and all of the green lines should be folded away from you (mountain fold) Crease well using a bone folder.

You should now be able to fold the card into shape and to decorate the centre as you wish. Good luck!