It sounds like you don't quite know how to maintain state yet. Here is a very basic example for you that uses a dispatch table of sorts. The actions are typically references to functions so that the script does different stuff for each action.

#!/usr/bin/perl -w
use strict;
use CGI;
my $q = new CGI;
print $q->header;
my $script = '/cgi-bin/tabs.pl';
my %actions = (
        tab1 => 'This is tab 1',
        tab2 => 'This is tab 2',
        tab3 => 'This is tab 3',
        summary => 'Summary',
        search => 'Search page',
);
my @tab_order = qw ( search tab1 tab2 tab3 summary );
my $action = $q->param('action') || 'search';
$action = 'search' unless exists $actions{$action};
display($action);
exit 0;

sub display {
    my $action = shift;
    my @tabs = map{ $action eq $_ ? "[$action]" : make_link($_) } @tab
+_order;
    my $html = "<p>@tabs<hr><p>$actions{$action}";
    print $html;
}

sub make_link { qq!<a href="$script?action=$_[0]">$_[0]</a>! }
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