Why not show some of the code you've done so far? Don't worry about it if you think it's really bad — that's why you came here right? :)

A few tutorials here:
• Variable Scoping in Perl: the basics
• Lexical scoping like a fox

From the perldocs:
• perlintro - scroll down to the section 'Perl Variable Types'

You've been given some good answers already but it's not a bad idea to get more familiar with the site's tutorials and the perldocs.