Hide text in posts

http://codex.ww.wp.xz.cn/Theme_Development
http://codex.ww.wp.xz.cn/Function_Reference/query_posts
http://codex.ww.wp.xz.cn/Function_Reference/the_post_thumbnail

<?php
query_posts( $args );
while ( have_posts() ) : the_post();
the_title();
the_post_thumbnail();
endwhile;
wp_reset_query();
?>

have you read those (3) pages?

put the code in index.php of your theme

or try
http://codex.ww.wp.xz.cn/Child_Themes