Blog post layouts wordpress - php

Question

I'm trying to create a different layout on my blog posts page depending on when the post is created. so blog post 1 will have one class while post two will have another and post 3 will have a final class. hard to explain but here is my code hopefully it will make more sense:
<?php
if(have_posts()):
while(have_posts()): the_post();
$counter = 1;
?>
<?php if($counter == 1){ ?>
<div class="new-row">
<div class="boxes picture-box contact-smaller-box">
<?php the_post_thumbnail(); ?>
</div><!--/.picture box-->
<div class="boxes white-box contact-smaller-box">
<div class="box-inner right-side">
<h2><?php the_title(); ?></h2>
<p><?php echo substr(get_the_excerpt(), 0,70); ?></p>
Read More
</div><!--/.box inner-->
<div class="arrow arrow-left"><img src="..."></div>
</div><!--/.white box-->
</div><!--/.new row-->
<?php $counter = $counter++; ?>
<?php } if($counter == 2){?>
<!-- second section of the blog post content -->
<div class="new-row">
<div class="boxes pink-box contact-smaller-box">
<div class="box-inner">
<h2><?php the_title(); ?></h2>
<p><?php echo substr(get_the_excerpt(), 0,70); ?></p>
Read More
</div><!--/.box inner-->
<div class="arrow arrow-right"><img src="..."></div>
</div><!--/.pink box-->
<div class="boxes picture-box contact-smaller-box">
<img src="..." alt="hearing aids for adults">
</div><!--/.picture box-->
</div><!--/.new row-->
<?php } ?>
<?php
endwhile;
endif;
?>
At the moment both of my test posts are showing as the first type of post, so im thinking my counter is not working correctly, or i have my divs in the wrong position to make this work. im new at working with php so i dont know where i am going wrong. any advice would be brilliant.

Answer 1

After about 4 hours of research and testing different things out i have found a solution (credit):
<?php if (have_posts()) : ?>
<?php $count = 0; ?>
<?php while (have_posts()) : the_post(); ?>
<?php $count++; ?>
<?php if ($count == 1) : ?>
Add your Custom Post Divs Here for the 1st post.
<?php elseif ($count == 2) : ?>
Add your Custom Post Divs Here for the 2nd post.
<?php elseif ($count == 3) : ?>
Add your Custom Post Divs Here for the 3rd post.
<?php elseif ($count == 4) : ?>
Add your Custom Post Divs Here for the 4th post.
<?php else : ?>
Add your Custom Post Divs Here for the rest of the posts.
<?php endif; ?>
<?php endwhile; ?>
<?php endif; ?>
hope it helps someone else out.