why the waves of the ocean go back and forth of the shore?

The waves of the ocean go towards the shore because of the presence of wind, which we sometmes call ocean current. These waves bounce once these reach the shore because their motion is halted and so their direction is reversed. It is just the same for a ball reaching a wall to reverse its direction. The reason behind the rising and falling of ocean waters lie on the gravitational forces of two celestial bodies which in this case, the earth and the moon, or at times, the earth and the sun. This phenomenon is a pulling effect brought about by the forces of gravities of these two bodies, hence the swelling of waters which we simply call tides. These tides once caught by the wind will form waves that flow to and from the shores.

Waves are seen to move through an ocean or lake; yet the water always returns to its rest position. Energy is transported through the medium, yet the water molecules are not transported. Proof of this is the fact that there is still water in the middle of the ocean. The water has not moved from the middle of the ocean to the shore. If we were to observe a gull or duck at rest on the water, it would merely bob up-and-down in a somewhat circular fashion as the disturbance moves through the water; the gull or duck always returning to its original position. The gull or duck is not transported to the shore because the water on which it rests is not transported to the shore. In a water wave, energy is transported without the transport of water.

The waves raise high and low...i mean the tides are due to the gravitational forces of the moon.This becomes intense during full moon

hhmm... isnt it because of the sun and the moon? wave current is caused by the pull between the sun and the moon... hence high tides and low tides during specific seasons..??