##-- code for making a session and passing the information
my $cgi = new CGI;
my $session = new CGI::Session(undef,undef,{Directory=>'/tmp/sessions'});
my $cookie = $cgi->cookie(CGISESSID => $session->id);
#print $cgi->header( -cookie=>$cookie ); #--do not print header first if you redirecting your URL as given below
$session->param('user_id',$username ); #--information passed

my $url = "http://localhost/cgi-bin/somesite.cgi";
print "Location: $url ";   #--redirecting the URL


##-- code for retrieving the information
print "Content-type: text/html\n\n";

my $cgi = new CGI;
my $sid=$cgi->cookie("CGISESSID");
my $session = new CGI::Session(undef,$sid,{Directory=>'/tmp/sessions'});

my $username = $session->param('user_id');
print "Username = $username";