Youdie
The key to adding ads to your gallery is your html templates. Learning those templates is not that difficult. Since they are html, you can place your code where you want.
For example:
home.html is your template for your galley home page. If you want ads to be placed on your home page, this is the template you may want to add your ad.
details.html is the template for the images (the larger photo after you click the thumbnail). If you want an ad to be in this area, add it to details.html
The templates are located under the template directory. For example the default templates are located at template/default
Make a backup of each html file before adding the ad just in case something does go wrong. It really isn't that difficult, it is a matter of trial and error until you get the ad in the template the way you want it to look.
My ads (adsense) are all over my gallery and they were all added in the html templates.
http://filipinaeyes.com/online-dating-gallery/