Ads are basically money in game. You can think of them as zeny if you like except you can do different things with Ads. For example, you can use Ads to buy items that are not easy to obtain ingame or isn't available in the item shop
http://anthemro.com/shop/. Or you can sell it for zeny.
1 Ads = 100 anthem pennies.
The current rate for 1 Ad is about 800k. So if you were to sell 1 Ad (100 anthem pennies) in game, then you could sell for about 800k.
or about 8k per 1 anthem penny.
To check the number of ads that you have, go here
http://anthemro.com/free/sponsors.php. It will be label as credit $0.00.
If you want to change your ad credit to anthem pennies, click on withdraw. If you want to convert anthem pennies that you have in game to ad credit so you can use to buy stuff in item shop, click on deposit (be sure to put your anthem pennies in the storage before you convert them to ad credit. Also, make sure its under the right account).
Hope this helps. If you still don't understand, I'll try to clear things up better.
