open my $FH, "<", "file.txt" or die "Cannot open file.txt $!";
while (<$FH>) {
    # ...
}

##</code><code>##

use strict;
use warnings;
use Data::Dumper;

my $sheet;
my $count = -1;

while( <DATA> ) {
  chomp;
  $count++;
  # skip header
  next unless $count;
  my $row;
  @$row = split( /,/, $_ );
  push @$sheet, $row;
}
#my @sorted = sort {$a->[0] <=> $b->[0]} @$sheet;
my @sorted = sort {$a->[1] cmp $b->[1]} @$sheet;
print Dumper \@sorted;

__DATA__
HEADER
1,Beginning C,Beginning C1
2,Beginning C++,Beginning C++1
12,navy blue,navy blue1
3,Python Intro,Python Intro1
8,Baker's dozon,Baker's dozon1
9,Jumbo frames,Jumbo frames1
4,Acme cook book,Acme cook book1
5,Jumping Jack Flash,Jumping Jack Flash1
6,Zebra,Zebra1
7,Ace hardware,Ace hardware1
10,Attack show,Attack show1
11,car 54 where are you,car 54 where are you1
13,navy gold,navy gold1

##</code><code>##

use strict;
use warnings;
use Data::Dumper;

my @sheet;

while( <DATA> ) {
  chomp;
  # skip header
  next if $. == 1;
  my @row = split( /,/, $_ );
  push @sheet, [@row];
}
my @sorted = sort {$a->[0] <=> $b->[0]} @sheet;
#my @sorted = sort {$a->[1] cmp $b->[1]} @sheet;
print Dumper \@sorted;

__DATA__
HEADER
1,Beginning C,Beginning C1
2,Beginning C++,Beginning C++1
12,navy blue,navy blue1
3,Python Intro,Python Intro1
8,Baker's dozon,Baker's dozon1
9,Jumbo frames,Jumbo frames1
4,Acme cook book,Acme cook book1
5,Jumping Jack Flash,Jumping Jack Flash1
6,Zebra,Zebra1
7,Ace hardware,Ace hardware1
10,Attack show,Attack show1
11,car 54 where are you,car 54 where are you1
13,navy gold,navy gold1