Featured Content Slider
Special posts deserve a special place. With Academica, every post assigned with a certain tag and given a featured image will be displayed in the Featured Content Slider on the home page of your site. To enable the slider:
Navigate to Settings → Reading.
Scroll down to the section labeled “Featured Content”.
Enter the name of a tag.
Click the blue “Save Changes” button at the bottom.
Once you’ve saved your changes, posts marked with this tag will appear in the featured content slider if they have a featured image. The suggested size for featured images is 960 pixels wide and 300 pixels high
Link to more on your theme>> http://theme.wordpress.com/themes/academica/