How do I stitch ´over 2´?

Pretend you are playing tic-tac-toe and draw the grid out on a piece of paper. Now, you would bring your needle up in the lower left corner and put it down through the upper right corner -- crossing over the square in the middle. Then to cross it, you´d come up in the lower right and down in the upper left, once again, crossing over the square in the middle. That is now once stitch done over two threads. Another way to help you count this while you are stitching is to bring up your needle in one hole, and then count two threads over and two threads up, and that is where the needle goes down.