Here are the steps to build a box:

1. Break down the box starting with opening the tabs on top and bottom of the box. Just unfold the tabs or cut through the tape with the box cutter and then unfold the tabs.
2. Lay the box down on its side and cut one of the corners from top to bottom so that you can unfold the cardboard once more to end up with a long, straight piece of cardboard.
3. Mark the corners of your box on the cardboard using a ruler and pencil.
4. Cut along your lines with a box cutter or scissors.
5. Fold along your lines to create creases in your cardboard.
6. Fold up your sides and tape them together.