Gravitational Force is the force of attraction between all masses in the universe. Its not a force of contact, but its that pull of that object back towards the earth, like the waves, or when one shoots a basketball, the force of gravity acts to pull the ball back to the floor.
Electrostatic Force is the phenomena arising from stationary or slow-moving electric charges. Its like the attraction of the plastic wrap to your hand after you remove it from a package.
Magnetic Force is the force that exists between two electrically charged moving particles. An example is like when you place a small magnet under a piece of paper and sprinkle iron filings on it and the filings are drawn to that magnet.