To the Original Poster:
The manuals   perldoc perlrequick   and   perldoc perlre   describe it quite well.

You will understand matija's solution after a quick glance into one of them and be able to use it.

$paragraph =~ m/FROM(.*?)WHERE/; # now everything in between is in   $1
my $inbetween = $1;

If that still doesn't make much sense, everything else can be found in   perldoc perlintro.

Cheers, Sören