The moon does have a effect on Earth's oceans, but the biggest reason why oceans are active, is the variation of temperature both in the atmosphere and in the water(This also creates a variation on pressure). The difference on air pressures, will create wind, which in turn create waves.

Ocean currents exist because different places on Earth are at a different temperature, and therefore the water will feel a pressure force to go elsewhere.

This is quite a generalization, but meteorology is a complex science, and there is much to dig in.