First: You should use an IDE like “Eclipse” or “PhpFireStorm”.
Second: Re-reading your code is always a good advice – what’s missing in the next line?
<img alt="<?php the_title(); ?> image"https://wordpress.stackexchange.com/questions/26142/<?php echo get_post_meta($post->ID,"img_url', true); ?" />
Third: You need to state global $post; at the beginning of your file, before you can access the provided data from the global post object.
Fourth: Never ever do something like this: <?php echo 'bla'; ?><?php echo 'whatever'; ?>. It doesn’t harm, but it’s aweful to read (and you should def. avoid it if you’re making money with code/webdesign).