ResBook doesn't just have the ability to include services in your bookings, but you can also create Add-On's. Add-on's differ from services in the sense that Add-on's allow for images to be added to them, and can be used to differ things like Breakfast etc. from things like Airport Transfers.
To create Add-ons, simply go into 'Settings > Stock Configurations > Services'. Click on any of the services you have created (Note: Service must be attached to a Stock Unit).
Once the pop-up menu appears, there will be a tab labeled 'Addon'. Click on this tab, and you will see a slider.
If you click on this slider, then the selected service will then become an Add-on. A test link will appear beside the button. This link will take you to the photo gallery for you to upload pictures of the Add-on.
Upload images, and you will have created your Add-on.