You will need
A cerial box
7pieces of Card
Double sided tape
Step 1: Make the front and back
Lay the pieces on top of your wallpaper, cut around the pieces adding 1" for folding over. Fold the excess over mitre the corners and use the double sided tape to hold in place. Now stick a piece of the card on each of the front and back sections to make it neat and hide the card.
Step 2: Bottom
Put the 2 covered front and back sections wrong side up on the table 4" apart. Now lay the piece you have just scored on the top so that the middle 4" is in the gap and stick the 2" sections to the front and back.
I hope that makes sense it is really hard to explain now i am typing. You will understand as you do it.
Step 3: Sides
Stick tape on each end and stick one end to the front and one end to the back. Go as close to the edge and the bottom as you can. Repeat for the other side.
Step 4: Sections
Stick into folds where you want them to go. I placed mine evenly. You could add more if you wanted.