Stitching over 1 vertically is done in a similar manner to stitching horizontally.
You still get an elongated diagonal stitch on the back of the fabric that will lock each stitch in place. Starting at the top, stitch from the lower right to the upper left ///////.
To complete the column of stitches, turn your fabric upside down, to keep your hand in a natural position and cross your stitches \\\\\\\.