Open the file yourself first and then hand it the filehandle.

#untested
open TFH, "main.html" or die "Can't open main.html cause $!";
my $template = Template->new() or die "new Template error $!";
$template->process(\*TFH) or die $tt->error(), "\n";

## or if you hate glob references maybe

use IO::File;
my $tfh = new IO::File;
open($tfh, "main.html") or die "Can't open main.html cause $!";
my $template = Template->new() or die "new Template error $!";
$template->process($tfh) or die $tt->error(), "\n";
[download]

The power of Template is the power of perl, there is more than one way to do things hidden in there. Very cool module. Keep trying with it.

Also, I'd recommend against putting the templates themselves in a subdirectory of your CGIs. That seems a bit insecure to me. Make a template dir at the same level as the CGIs and the docroot and save yourself some worry.

--
$you = new YOU;
honk() if $you->love(perl)