scream2ice 0 Light Poster

i want to write an object oriented program using classes and sequential files

there is a store which keeps record of its customers' info in a file:

customer code char6
customer name char30
total cost of products bought so far long int
owe long int
date of last purchase char8
contact info char50


i wanna write a program that reads today's date from keyboard and provides a list of those customers who's owe is
more than $10 and it pasts more than 30 days from their last purchase date.
iwant this list to be saved in a file called "ngbal.txt"

i don't want the whole code....just a hint on how to get started and get teh program structure well
what do i need to consider a class and object and....
plz help