Ok, so you want to simply sail up and down, here are a few tips to help you get going.
First make sure your equipment is suited for you and make sure it's rigged correctly, for example, if the boom is too high or too low you will feel uncomfortable.
Sailing in a straight line is easy if you keep your body relaxed and looking forward. If you are too stiff you will not glide over the chop and you will tire very quickly. Closing and opening the gap (sheeting in and out, or opening or closing the sail), is all done with your back hand. When you sheet in you power up, when you sheet out you slow down. When in doubt, sheet out. Always look into the direction you are sailing and never look down at your feet as this will through you off balance.
You also need to know how to turn upwind (into the wind) and downwind (away from the wind). When you turn upwind, the wind will start to blow more into your face rather than your back, if you go downwind the wind will start to blow against your back. In order to turn upwind, move the back of your sail (the back end of the boom) down toward the back of the board. If you had to touch the back of the board with your sail, you will begin to turn too far upwind. To turn downwind, sheet out slightly and tilt the head of the boom toward the nose of the board.