You'll need a modification. The best way to determine what you need is to search through the various advertising mods available and decide what will work best for you. If you have questions as far as comparing one to another, we can help.
To find the advertising mods, use the search in the upper right of this page and search for
advertis*
All Mods
Titles only
You might want to check the 3.7 mods that show up as well since many of them will work with 3.8 as well.
One that might not come up in those results is
vB Ad Management since it only contains "ad" in the title.