Sharon Murphy on "[Plugin: All-in-One Event Calendar] Custom MySQL query?"

First, make sure you have support for featured images turned on in your theme. Check your functions.php file to see if this line is in there:

add_theme_support( 'post-thumbnails' );

See this link for more info.

In your template ai1ec-sample-usage.php, you should have this line:

<?php the_content(); ?>

Wherever you want the thumbnail image, do this:

<?php if ( has_post_thumbnail() ) {
    the_post_thumbnail();
} ?>

There are specific sizes you can generate through the functions.php file as well, and then you can add more customization inside the parenthesis for this hook. If you would like more help, please feel free to reply here or message me privately.