This is actually a (potentially) very complicated thing. What I would do is the following:
- Define the problem better. Are you going to do just static pages? What defines if a page is in a given site? There are a lot of different answers, and none are really wrong.
- Learn how to do the part where they enter a the URL (and word?) and figure out how you can do something with it.
- Learn how to return information back to them.
- Then, and only then, are you ready to learn how to walk a website (probably using something similar to WWW::Mechanize).
In other words, I would recommend the following:
- Read Learning Perl, by Randal Schwartz.
- Play around with website development
I hope your homework isn't due in the next week, or so.
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We are the carpenters and bricklayers of the Information Age.
Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.