How to access a method inside my plugin

Hey guys,

Below is a very rough outline of a plugin;

<?php

/*
Version: 0.1
*/

add_action('admin_menu', array('MBH_Team_Manager', 'admin_menu'));

register_activation_hook( __FILE__, array('MBH_Team_Manager', 'activate'));
register_deactivation_hook( __FILE__, array('MBH_Team_Manager', 'deactivate'));

class MBH_Team_Manager {

	function admin_menu(){
		add_pages_page('The Team Management', 'The Team', 'publish_pages', 'mbh_team_manager', array('MBH_Team_Manager', 'admin_options'));
	}

	function admin_options(){
?>
<div class="wrap"><div id="icon-users" class="icon32"></div>
<h2>The Team Management <a class="button add-new-h2" href="edit.php?post_type=page&page=mbh_team_manager&action=add">Add New</a></h2>
<br />
<?php
		if(isset($_GET['action']))
		{
			if($_GET['action'] == 'add')
			{
				$this->add_new()
			} else{
				$this->list_team();
			}
		} else {
			$this->list_team();
		}
?>
</div>
<?php
	}

	function list_team(){
?>
list team
<?php
	}

	function add_new(){
?>
add new
<?php
	}

	function activate(){
		//create table
	}

	function deactivate(){
		//delete table
	}

}

You should be able to see the if statement if(isset($_GET['action'])). Following this I want to call one of the classes methods, but wordpress does not allow me to do this.

What should I be running in place of $this->list_team(); to access a method from another method?

Cheers,
Gareth