Show us runnable sample code that demonstrates the problem. Note that template loops with nested data require a nested data structure so your sample code should show us how you create that structure. Most likely you want something like:

use strict;
use warnings;
use HTML::Template;

my $html = <<HTML;
 <TMPL_LOOP NAME="files_loop">
   <tr id="TMPL_VAR ID>">
     <td><TMPL_VAR NAME ="index"></td>
     <td><TMPL_VAR NAME ="filename">   </td>
     <td><input type="checkbox" name="field" <TMPL_VAR NAME="check">>
     </td>
   </tr>
</TMPL_LOOP>
<form action="index.cgi" method="post">
    <input type="submit" name="Edown" value=" Download ">
    <input type="hidden" name="cmd" value="download">
</form>
HTML

my $tmpl = HTML::Template->new(scalarref => \$html);
my @loopParams = (
    {index => 1, filename => 'plonk', check => 'f1'},
    {index => 2, filename => 'pip',   check => 'f2'}
    );

$tmpl->param(files_loop => \@loopParams);
print $tmpl->output();
[download]

prints:

 
   <tr id="TMPL_VAR ID>">
     <td>1</td>
     <td>plonk   </td>
     <td><input type="checkbox" name="field" f1>
     </td>
   </tr>

   <tr id="TMPL_VAR ID>">
     <td>2</td>
     <td>pip   </td>
     <td><input type="checkbox" name="field" f2>
     </td>
   </tr>

<form action="index.cgi" method="post">
    <input type="submit" name="Edown" value=" Download ">
    <input type="hidden" name="cmd" value="download">
</form>
[download]

I have my cgi script very similar to what you have. hastable contains the filenames to be output it. I don't have the f1,f2...values for the check, not sure if it's needed.

$q = new CGI;
$template = HTML::Template->new(filename => "$displaypage",
                                          associate => $q);
  my @loop;
  foreach $index (sort {$a <=> $b} keys %hashtable) {
    my ($fn) = @{$hashtable{$index}};
    my %row = (
       index => $index,
       fn    => $fn ,
       check => " ");
       push (@loop, \%row);
  }
  $template->param(files_loop=>  \@loop);
  send_header();
  print $template->output;

[download]

so after user click on the checkboxes for the files that he wants to download, then he click on the "download" button, in my cgi script it will go to "sub downloadFiles", in here I am not sure how to get the values of the checkboxes or filenames , I tried this :

  sub downloadfiles {
   @files = $q->param("field");
    ...
  }
[download]

It did not get any values in @files. Not sure what values it should returned. I tried you suggestion adding f1,f2 with instead using index number 1,2,3... but still don't know how to get the checkboxes values. Please help.

Oh, silly me. You don't provide a value attribute for your checkbox so nothing gets returned. You need something like:

     <td><input type="checkbox" name="field" value="<TMPL_VAR NAME="fi
+lename">">
[download]

for your checkbox line. That will return the file name if the checkbox is checked.

True laziness is hard work

<td><input type="checkbox" name="field" <TMPL_VAR NAME="check"> value=
+"<TMPL_VAR NAME ="filename">"
[download]

Could you show me how to get the the names of checkbox or filenames with your added value="<TMPL_VAR NAME ="filename">"

Look here http://search.cpan.org/~markstos/CGI.pm-3.60/lib/CGI.pm#FETCHING_THE_VALUE_OR_VALUES_OF_A_SINGLE_NAMED_PARAMETER: