To show the Photo Browser palette:
Sources
Use pop-ups to show pictures from your iPhoto albums or Pictures folder.
Pictures in selected source
Drag and drop pictures from the Photo Browser palette to add them to your composition.
Search
Use Search to find images in your albums or pictures folder, depending on what is selected as a source.
Open imagesDouble-click on image thumbnail.
Add images to compositionsTo add layer, drag & drop image thumbnail on opened composition.