PHP for beginners

<?php

	$var = 3;

	echo $var;

	echo 'I am a string';
	echo "I am a string";

	echo 'I am $var';		//output: I am $var
	echo "I am $var";		//output: I am 3
	echo 'I am ' . $var;	//output: I am 3

	echo 'I ' . 'am ' . 'a ';
	echo 'I am a';

	for($i=1; $i<5; $i++) {
		//echo '<div class="asdfasdf">all my html is inside an echo</div>'	// BAD!
?>
		<div class="row<?php echo $i?>">
			<div class="card">
				<img src="flickr_url.jpg">
			</div>
		</div>

<?php

	} // close for loop
?>

<?php

	$arr = array('flickr_url1.jpg','flickr_url2.jpg','flickr_url3.jpg')

	cols(array('flickr_url1.jpg','flickr_url2.jpg','flickr_url3.jpg'))
?>