Hi,
The perldoc says about lib:-

"This is a small simple module which simplifies the manipulation of @INC at compile time.
It is typically used to add extra directories to perl's search path so that later C<use> or C<require> statements will find modules which are not located on perl's default search path."

The @INC variable is set to look in the various places AND the current directory:
mine is set for these paths:-
/usr/libdata/perl/5.00503/mach ,br> /usr/libdata/perl/5.00503
/usr/local/lib/perl5/site_perl/5.005/i386freebsd
/usr/local/lib/perl5/site_perl/5.005
and .

so if I want to 'use'/'require' .pl progs in say /home/perl then I can specify that in the code as

use lib /home/perl; # note lib will take a list

then I can 'require' or 'use' anything in that directory.

Hope this helps some.

Cheers
Steve