Is this a Perl question, or is it that you have never programmed before and start learning to program using Perl, so it's more like a general programming question? From the way you ask, I suppose the latter, but you should make this clear, because you can get better help if we know about your current level of knowledge.

For instance, Perl offers several ways to iterate over an array, so for a Perl-newbie, I would refer him or her to perlsyn, in particular the sections about looping (because people new to Perl usually don't know which part of the huge documentation contains what they are looking for]. However, if I know that you have never programmed before, this information won't help you, because you don't even know what "looping" means, and we would have to teach you basic skills first.