I make this style of card regularly for Crafters Companion as it is very popular. It's simple to make using the Top Score tool.
All you need to do is place a sheet of A4 cardstock with one of the short edges against the rest. Score along the tri-fold A4 line. Turn the card over so that you can score the same line again from the opposite end of the card. You now have a piece of card that is scored into equal thirds.
To get the decorative edge, place two of the three thirds against the wavy line on the board and score as shown. Cut away the section above and including the embossed line and fold the card in a zigzag. You can now decorate the three forward facing panels however you want!