Once you've established which way you stand, it's time you learn how to push. Keep your front foot planted firmly on the board just behind the front truck bolts. Keep all your weight centered over your front foot, and try pushing with your back foot. It takes a little while to get used to the balance, but after some practice it will feel more natural.
Once you have a little speed going, put your back foot on. If you've never stood on a skateboard before, it can be scary at first, but after a while you'll get familiar with how it feels to roll. Just cruise around and get comfortable with your board; try turning from side to side by leaning one way, then the other. Get used to the balance of everything, and watch out for rocks and cracks.
