Adding subtitles into a horizontal menu

What would i have to edit to accomplish this look in my menu?

https://wptest.gadgetwebdesign.com/wp-content/uploads/2012/03/menuwithsubheads.jpg

I want subheads in my horizontal menu. I have searched in the forums and on the web and I found this website under “Adding Sub-Titles To Menu Links” but that doesn’t look like anything in my php files at all.

At least the tutorial mentions putting it in the header.php and I don’t find anywhere where this code might work. Here’s my header.php code… if anyone can point me in the right direction I’d appreciate it. I’m learning a lot about wordpress templates, but I’m not quite there yet where I can spot the correct code at a glance.

[54 lines of code moderated as per the Forum Rules. The maximum number of lines of code that you can post in these forums is ten lines. Please use the pastebin]

And in case you need it, the only other php file that looks like it might have relevant code is the navigation.php file (below)

[390 lines of code moderated as per the Forum Rules. The maximum number of lines of code that you can post in these forums is ten lines. Please use the pastebin]