I want to know what electricity actually is? Is it flow of electrons or they just vibrate and pass on the enrgy and if its so what's the need of free electrons? And is the a surface phenomenon or a bulk one. Moreover I would like to know what actually constitutes and contributes for "Electrical Energy" when current remains same across the resistance, then in what form energy is being used ?

Electricity is physically the movement of electrons along a conductive path. The individual electrons themselves don't actually move very fast, but the effect of their movement is transmitted along the conductor at almost the speed of light (depending on the conductor). It's kind of like pulling on a rope - if you have a 100 meter long rope and pull on one end at 1 meter/sec, the other end of the rope starts moving at 1 m/s almost instantly - so the effect of the molecules moving at one end of the string is felt by the molecules at the other end alnmost instantly, even though the individual molecules are moving at only 1 m/s. For DC current flow the electrons migrate down the conductor in one direction. For AC flow they first flow one way and then the other - with a "push-pull" effect.

As for how energy is used across a load - the resistance of the load inhibits the flow of electrons, resulting in release of heat. In the case of a light bulb, some of the energy goes to energizing the elctrons of atoms in the filament so they can kick out photons.