This is a fun fold that creates a diamond in the front of your card for the top flap to slip into. Here is what it looks like when you open it up.
The basic fold for this card is pretty easy. You start with an 11 x 11 sheet of paper folded in half diagonally. Line this fold up with the top of your score board and one corner at the 0-mark. Then score at 3 1/4" (the instructions said 3 1/8" but for some reason 3 1/4" lined up better for me) and 5 1/2". Flip it over so the opposite corner is at the 0-mark and repeat the scoring. This gives you 4 perpendicular scored lines (see drawing below).
Now your card is pretty much done, but the edges are open all around. The only edges you want to leave open are the front diamond that you will tuck the top flap into. The other diamond will be on the inside of the card and doesn't need to be left open. Soooo. Glue all around the edges EXCEPT for that diamond that you want to leave open. Press all glued edges closed and you are ready to decorate your card.