"It would be helpful if anyone provide me some code examples."

#!/usr/bin/perl -wT
use strict;
use CGI qw/:standard/;

my $logo = '/path/to/logo.jpg';

print header,
    start_html,
    img {src=>$logo };
[download]

"I am new to Perl CGI."

Two recommendations:

1. Use CGI.pm
2. Check out Ovid's CGI Course.

Cheers,
Darren