You might think about using a DBM file instead of a flat text file... DBMs associate keys with values, so you could associate user names with their content.

You might use something like this:

use DB_File;

my %users;
my $file = "foo";
tie %users,  'DB_File', $file, O_CREAT|O_RDWR;

$users{'User1'} = <<HTML;
<center>
<h1>Hello!</h1>
</center>
HTML

my $html = $users{'User1'};
print $html;
[download]

That's just an example; but it might make your life a lot easier, because then you wouldn't have to worry about carriage returns and the like.