If you like to replace featured.png and headline.png images above these sections in Arthemia, that's easy:
first edit style.css and add somewhere (best is at the end to find it again):
span.textimg {
font-size:1.7em;
}
here you can change the font face, -color, -weight etc later
now edit index.php and replace the line:
<img src="<?php echo get_option('home'); ?>/wp-content/themes/arthemia/images/headline.png" width="75px" height="21px" alt="" />with a text entry in a span:
<span class="textimg">Headline</span>now reload the page and look if you like it. You can change the text 'Headline' to what ever you like. Doing the same with the line calling featured.png will give you what you asked for.
eg just also replace:
<img src="<?php echo get_option('home'); ?>/wp-content/themes/arthemia/images/featured.png" width="72px" height="17px" alt="" />with
<span class="textimg">Featured</span>