Explain how force and energy change are related?
This is a very good question, although a difficult one!
When energy change (from a form to another) it does it through WORK which is basically Force times Displacement (ok, it is a little bit more complex but do not worry now).
Consider a stone that falls from a cliff. Potential Energy (due to the initial position of the stone with respect to the ground) changes into Kinetic Energy (due to the velocity of its movement during the fall) through the intermediation of the Work done by the Gravitational Force during the displacement from the top to the bottom of the cliff.
The definition of Work is a little bit complex because it involves vectors and, if the force varies, integrals:
in general you have:
I do not want to complicate your life too much but you may have a thermo-dynamical version of Work that involves pressure (force over area) and change in volume.
The important thing, however, is that every time Energy changes its form it does this through Work that involves a Force.