Stephen on "Timthumb to native Wordpress image resized thumbnail"

My old line I'm trying to replace is as follows.

<img src="<?php echo bloginfo('template_url'); ?>/thumb.php?src=<?php echo $post_images[0];?>&w=105&h=70&zc=1&q=80<?php echo $thumb_url1;?>" alt="<?php the_title(); ?>" title="<?php the_title(); ?>" />

I've tried using the_post_thumbnail but not sure how I should be using it. Also seen http://matthewruddy.github.io/Wordpress-Timthumb-alternative/ but not sure how to use it as it lacks documentation, so not sure the right way to implement it.

Any suggestions, would be gladly appreciated it. Thanks.