How force is transferred from one body to another If there are 3 coins , namely 1 , 2 and 3 as in figure.
When coin $1$ strike coin $2$ ,the coin $2$ passes the force to coin $3$ and the coin $3$ moves away.

Case :1
 How does this happen?
 What exactly happens there and passes the force on coin $1$ to coin $3$?
 How does the force cause movement?
 I mean that when we push any object, why does it moves?
Case 2:
What will happen if there are just 2 coins and coin $1$ strikes coin $2$ and coin $2$ moves?
How and why does coin 2 move in this case?
Please don't say that there is no opposite force or net force is not equal to 0.
 A: Here is a very simplified picture:
Let's say you have a slow motion camera, and you can see in detail what happens in the fractions of second it takes for this process to occur. What you would see is that when 1 and 2 start touching they start deforming a bit. 
This deformation is kinetic energy of 1 transforming into potential energy of 1 and 2... and just a bit later into potential energy of three as well, since 2 is compressing and exerting compression on 3 as well. Well instants later all this compression was transformed into the force that put 3 into motion. 
Now why did 2 stay in its position? Well we are assuming that at least 1 and three have equal masses, if this was not the case, then the result would be different. We are also assuming the knock was completely elastic. This means that all energy stayed kinetic, no coin remained with internal energy, that is none stayed deformed, not even vibrating.
Still, how to explain that 2 stayed? Well since 1 and 3 are identical, the deformation on 1 when hitting two is instantaneously transmitted to 3 through 2. This happens only when 2 is very small or very strongly made (so that compression on one side travels so fast that no portion of 2 can move faster with respect to the other, this is close to an ideal solid). 
If this were not true, then 2 would deform and the transmission of movement to 3 would take longer time, and 2 would move some distance before completely giving its internal energy to kinetic energy of 3.
So basically, the system behaves much like if 1 hitted 3 directly, and 2 remains a spectator.
A: A different example from your coins, but the same idea, is Newton's cradle. 

Pull one ball away, it hits the first ball in the line and comes to nearly a complete halt. The ball on the opposite side, like your coins,  gets most of the initial velocity and almost instantly swings in an arc nearly, but not quite as high as the height of ball you dropped at the start. 
This example demonstrates that the final ball receives most of the energy and momentum that was in the first ball. A wave of compression moves through the intermediate balls. 

I mean that if any force is applied on a body how does the body moves.This could be a foolish question but i am really stuck on it. 

As to how a force makes a body move, the second body has no choice but to move, if can move freely, because of the law of conservation of energy. Possibly, rather than thinking about how the body moves, ask yourself, what would happen if bodies did not move when a force is applied to them? 
