The other suggestions thus far assume a line-by-line read of the file, if you're slurping the file in, howz about...

my ($first, @rest) = <DATA>;
warn "first: $first";
warn "rest:\n@rest";
__DATA__
header
line1
line2
[download]

user@unforgiven:~$ perl tst.pl
first: header
rest:  line1
 line2
user@unforgiven:~$
[download]