Hi there, do you mean the tag line like in the demo – http://screencast.com/t/efypp6O6l4l
If so, go to appearance>theme settings>general from the WP admin. Scroll down to the header tagline area, enter your chosen text and save. http://screencast.com/t/2DpzFKkM
Otherwise, if you’re looking to add additional text into that area, inbetween the logo and the tag line, you’ll need to add manually to the header.php file as html at around line 82.