Resize uploaded image before copying to directory

Hey all,

With limited knowledge, I've managed to get my file to upload to a temp directory, then move to my chosen folder and copy to a second folder. I'm trying to work out how to resize the uploaded image to 500px wide (while maintaining the aspect ratio) before copying it to /zoom and resizing again to 100px wide before copying it to /thumb. I've spent ages looking at tutorials but don't know php enough to work out how to crowbar any of the solutions into my code. This is the final hurdle before I can finish my site so any help would be hugely appreciated! Thanks guys

if (empty($errors)) {
	if (move_uploaded_file($file_tmp, '../images/products/zoom/'.$name) && copy ('../images/products/zoom/'.$name, '../images/products/thumb/'.$name)) {
		echo 'Done';
	}
		else {
			echo 'error';
		}