Update Oct 29: This is a Visual Guide to Ads in XenForo 1.x. XenForo 2 Visual Ad Guide is Here.
XenForo’s default style has 19 ad locations.
Here is the visual guide to how each one of them is placed.
1. Home (forum_list)
2. Forum (forum_view)
3. Thread (thread_view)
4. Member (member_view)