When you first begin skateboarding, the first step will be to figure out if you are goofy or regular footed. If you prefer to have your left foot forward, you are regular footed. If you prefer to have your right foot forward, you are goofy footed. Test out which foot feels more comfortable as the front foot.
Once you figure out which foot should be forward, place that front foot by the nose of the board, either behind the bolts or right on top of the second set of bolts. After getting your front foot set, you will want to place your back foot in the same position, but on the tail end of your board. With your feet stationed on the board, stand in an upright position to control your body. Your posture will influence your control while riding.
Push off with your back foot, keeping your front foot on the board. How you turn will depend on your skateboard. One way to turn is to use your bodyweight and lean it in the direction you want to go. Another way is to lean on the tail end of your board to lift up the nose and spin in the direction you want to go. To stop, you can drag your back foot along the ground and slow yourself down until you come to a complete stop. You can also hang your back foot halfway off the tail and use your heel to make contact with the ground.