Form script is as follows
its simply a guest book which will first take the values given by the user and then print all the values which are till now given by the users

#!/usr/bin/perl
#script to take the values from the form

print "Content-type: text/html\n\n";

&read;

    open("f1",">>comment");
    select(f1);$|=1;
    print $Hash{'comment'},"\n";
    print "   by: ",$Hash{'name'},"\n";
    print "\n";
    close(f1);
    select(STDOUT);$|=1;
    print "<title> The form response</title>";
    print "<body bgcolor= \"fffff9\" >";
    print "Here are the comments<p>";
    open("f1","comment");
    while($line=<f1>){
     print "<pre>",$line,"<p>";}
    print "<p></ul><hr>";
    ###printing the environment variable i use it only for to know but they have no need in program#
    # so i just comment them                                                                                                              ###
    #print "Here are the environment variables:<ul>";
    #foreach $key (keys %ENV) {
     #print "<li>$key: $ENV{$key}";
    #}
print "</ul></body>";

sub read {
local ($i,$key,$val);

if($ENV{'REQUEST_METHOD'} eq "POST"){
read(STDIN,$Hash,$ENV{'CONTENT_LENGTH'});
}

@Hash = split(/&/,$Hash);
#$i=0;
foreach $i (0 .. $#Hash){
$Hash[$i] =~ s/\+/ /g;
($key,$val) = split(/=/,$Hash[$i],2);

$key =~ s/%(..)/pack("c",hex($1))/ge;
$val =~ s/%(..)/pack("c",hex($1))/ge;

$Hash{$key} .= "\0" if (defined($Hash{$key}));
$Hash{$key} .= $val;
}
return length($Hash);
}

Note
be carefull about the permissions of the file in which you put the comments.It should be writetable by the others.

Demo of program