can any body help me to explain how data files stored to the memory?

Answer 1

data is stored as a series of tiny indentations (pits). The areas between pits are known as 'lands'. So imagine a laser hitting the pits then the "lands". there is a difference when the laser is bounced back to the detector . these will give u the rough idea of how data is stored.

For more details, go to the wiki site below and read up on the physical details. the 2nd link will show u the pits and lands converting to binary code.