When i was a child i didn't know what Halloween was and of course because of that i didn't celebrate it either. I first heard about Halloween just after the Romanian revolution when lots of TV channels started to appear out of the blue and of course the movies came around as well.
The first ever movie about Halloween was the movie "Halloween" of course with Jamie Lee Curtis. I am sure that probably everybody in the western world already watched it but if you didn't have the chance then i am highly recommend it.
In England, Halloween is celebrated everywhere and kids look forward to it as it means they are allowed to eat lots and lots of CANDY! Kids hear about it first at nursery and cartoons i guess. I remember that we didn't introduce Halloween to Kara. It was the nursery that did it through the celebrations that they had at nursery.
Another reason why the kids love it is because they love dressing up and decorate the pumpkin.