Font in php/gd?

Can someone tell me how I would change the font face/size (the font that GD generates on the image) in the following script?

The text lines are bolded. I am stumped. I've been googling php/gd tutorials all morning, and nothing I have tried has worked. Any suggestions?

Thank you!

<?php 
header("Content-type: image/png"); //This script IS the image.
require_once('includes/Config.inc.php'); // Keep the config seperate.
require_once('includes/Mysql.inc.php'); // Never forget the MySQL abstraction layer.

if(isset($_GET['serial'])){$serial = $_GET[serial];}
else{$serial = $default_ticker;}

$result = $db->query("SELECT start, end, event, banner, slider FROM Ticker WHERE id='$serial'");
list($start_date, $end_date, $event, $banner_image, $slider_image) = $db->fetch_row($result);

$today_date = time();
$current_step = round(((($today_date - $start_date)/60)/60)/24) - 1;
$interval = round(((($end_date - $start_date)/60)/60)/24);

$remaining = $interval - $current_step;
if($remaining == 0){
	$string = [B]$event." has arrived!";[/B]
}elseif($remaining == 1){
	$string = "[B]Only $remaining day left until ".$event[/B];
}else{
	$string = "[B]$remaining days until ".$event;[/B]
}

if(!is_file($banner_image)){
	$banner_image = $default_banner_image; //"banners/ruler-10300.png";
}

if(!is_file($slider_image)){
	$slider_image = $default_slider_image; //"sliders/icon-104.png";
}

$banner = imagecreatefrompng($banner_image);
$bannerheight = imagesy($banner);
$bannerwidth = imagesx($banner);
$one_step = (($bannerwidth - 20) / $interval);

$black = imagecolorallocate($banner,0,0,0);

// Numbers on the bottom of the banner.
$count_step = round($interval / 12);
$count = $interval;
$count2 = 0;
while($count>=0){
	$px = (($bannerwidth - 20) / $interval) * $count2 + 5;
	$interval_height = $bannerheight - 25;
	imagestring($banner, 2, $px, $interval_height,$count, $black);
		$count = $count - $count_step;
		$count2 = $count2 + $count_step;
}

$slider = imagecreatefrompng($slider_image);
$sliderheight = imagesy($slider);
$sliderwidth = imagesx($slider);
$slider_location = $one_step * $current_step + 5 - ($sliderwidth / 2);

imagecopy($banner,$slider,$slider_location,0,0,0,$sliderheight,$sliderwidth);

$string_height = $bannerheight - 13;
$px    = (imagesx($banner) - 7.5 * strlen($string)) / 2;
imagestring($banner, 3, $px, $string_height, $string, $black);

imagepng($banner);
imagedestroy($banner);
//imagedestroy($slider);
?> 

Code (markup):

 

To use font on php images use the function described here

And here you'll find a program to generate the font image

 

Or here using imagettftext function: http://php.mirror.camelnetwork.com/manual/en/function.imagettftext.php - You'll need freetype support on GD.