I would like to know how an object can reflect light?Does the object must first absorb a photon with energy equal to the energy difference between two orbitals of atoms,so that it can reflect colour when the excited electron release energy with frequency equal to visible light's frequency?

 

Another question is that where does the energy goes to when an object absorb light which is not the colour the object possess?

The reflection is the opposite of what you describe — the color of an object arises because of the light the material doesn't absorb. Something that looks red does so because it reflects red light and absorbs blue (and blue, and on into the UV, being more energetic, can destroy chemical bonds, which is why red colors tend to fade)

 

Absorbed light that is not re-emitted eventually ends up as phonons, i.e. vibration states, which shows up as an increase in temperature.