What arthas said, except you may want to change the name of the file if the data is different each time and you want to keep it. Like so:

my $filename = time();

my $doc = '';
open (MYOUT, ">/mypath/$filename.html") or die $!;
$doc .= "<p>Mydata....</p>";
$doc .= "<p>Myotherdata....</p>";
print $doc;                 # This goes to the web browser
print MYOUT $doc;           # This goes to a files
close (MYOUT);
[download]

You may also want to add a piece of code to clear out the old files after a specified number of days:

my(@files, $file);
  opendir(DATADIR, "datadir");
  @files = grep(/[0-9].html/,readdir(DATADIR));
  closedir(DATADIR);
  foreach $file (@files)
   {
    if (-M "data/$file" > 30)
     {
      unlink("data/$file");
     }
   }
[download]