In my menu, I want to add some text under the menu item. For example, I have 'About Us', and right under that, I want some subtext 'About our company'.
Do I add this in region.tpl.php?
Use superfish module for building your menu, and then whatever you type in your description depend on configuration will be print out too.
Under Advanced HTML
Settings > Hyperlinks enable the "Include hyperlinks description (title) in hyperlinks text."
then simply add a
display: block; style to the
ul li a span to make it look the way you want.
you can see a demo HERE