Go to Settings -> Navigation Manager
Click 'Add Tab'.
Enter as in image.

Now add the sub menu.
Select 'Add Link'

You will need to add 3 Links.



Now you need to add a Plugin
Go to Plugins & Products -> Plugin Manager
First - Disable the Plugin oscShop process_templates_complete
Now - Add New Plugin

This is the code for the Plugin
PHP Code:
if (substr(THIS_SCRIPT, 0, 4) == 'osc_')
{
$request_tab = 37;
}
This is where you get you Nav Tab ID
Go to Settings -> Navigation Manager
Click Edit for the Shop Tab.

You should now have a Shop Tab and Sub Menu showing in your Nav Bar.