Let us start off with Chapter 1 :
Chapter 1 Oceanography
             

So, what are ocean currents?  Ocean currents are streams of water moving along the surface of the ocean like rivers in a definite direction.
Ocean currents are divided into two categories which are  Warm currents which carry warm water from the equator towards the poles and

 this video explain the movement of ocean currents and factors that effect them

 Cold Currents which carry cold water towards the poles.

 currents rotate clockwise in the northern hemisphere and anti clockwise in the southern hemisphere