tony_hk,
Airspeed is entirely unrelated to windspeed.
Airspeed is the speed of the aircraft through the air.
Wind is the movement of that air over the ground.
In ideal conditions, what the air does over the ground has no bearing on what the aircraft does through the air.
I can't really do any better than the moving sidewalk analogy other than to reiterate the distinction between moving from one airmass to another (windshear), to flying within the one airmass (a steady non-turbulent wind).
In the former case airspeed changes momentarily and is the subject of this thread. In the latter, the airspeed stays constant for a given power setting and aircraft attitude (climbing or descending) regardless of whether it is a tail wind or headwind, and is often confused with the subject of this thread.
Anyone's free to PM me, though I'm no more qualified than the others around here.