Add and replace assets
Ad templates have placeholder assets and descriptive IDs for each element. To create an ad from a template, you can just replace each generic placeholder asset with an appropriate one for your ad. Ads created from templates are completely modifiable; you can add or delete assets, components, and events as you wish to create a more customized ad.
To replace an image in your ad with one in the asset library, right click the image you want to replace, and select "Swap image..." from the pop-up menu.
In the dialog, either select an image from the asset library or click "Browse" to select an image from your computer.