Hey luckyali.

For 1) A PDF represents eitheru) the probability of getting a particular event (if it is discrete) or it represents a function that is used to obtain the probability of a non-zero length interval (in the case of a continuous distribution).

The PDF can be interpreted in different ways but you should think of it as showing the long term behavior of the stochastic process if you carried out the process and infinite number of times.

Hint: For your other problem you can get a PDF by taking a set of frequency data and dividing all cells by the total frequency count (i.e. the sum of all frequencies).