From a skateboarding how-to:
Foot placement for manualing is important. You'll want to have your back foot covering most of the tail of your skateboard, and the ball of your front foot right behind your front trucks. Take a look at the photo to see.
Now remember - there is no right or wrong way to skateboard! So, if you feel more comfortable with your front foot more toward the nose of your skateboard, or back more, or even over to the side - feel free. Do what works. But, right at the start, I recommend putting your feet in this position. It works best for most people.
What is the meaning of "over to the side"?
With your foot hanging in the air?
Or "with the ball of your foot shifted to the left or to the right of the imaginary axial line running through the board lengthwise"?