use CGI qw/:standard :html3 :all/;
use strict;

sub check_login{

....

}

sub display_header {
 my $disp_text=$_[0];

 # Note that I have to create a new CGI object here in the sub
 my $query = new CGI;
 print $query->center;
 print $query->table( { -border=>0},
        Tr([ td( {-align=>"center" },[ $query->img({-align=>"center", -src=>"logo.gif ", -border=>0 }),                $query->font({-size=>'4'},$query->b( $disp_text)),
             ]),
       ]),
);

}

sub display_footer{

...
...
}