smandula,
The first number is the control number. It is not meant to be read by the players and is used as a security feature. It is used to prevent anyone from producing a fraudulent ticket. For example, after a draw it is easy to produce a ticket with the winning numbers because the winning numbers are known. What cannot easily be done is produce the correct unique control number to match the winning ticket.
The next two numbers are dependent upon which jurisdiction produced the ticket. The use of those numbers varies across the country. One number is the retailer number. It uniquely identifies which retailer printed the ticket. To find out which number it is in your jurisdiction, just look at two tickets from the same retailer and the number will be identical on both tickets.
The third number is another security number that is jurisdiction dependent.