Gail,
Take an 8 1/2 x 11 piece of cardstock and cut it in half so that you have 2 pieces that measure 4 1/4 x 11.
Next, fold the 2 pieces of card stock in half. They now measure 4 1/4 x 5 1/2.
Now, unfold both pieces. Glue them together so that they overlap in the middle. When this is done, there will be two pieces that fold over top of your double layer you just made. ( I hope that made sense...)
Next, cut the 2 pieces that fold over the overlap part at angles. One in one direction and one in the other. Start by drawing a line from the top of the crease in your fold to the bottom edge on the opposite side. Then cut. Make sure that your angles are in opposite directions.
Then all that is left is to glue it together. I use sticky stirip along the bottom and sides.
Does that help any??? If not, let me know and I'll see if we can figure out something else.