Add frames to your photos with the frame tool. To find this tool, click on the Frame button in the Creative tab, then select Image Frame.

Once Image Frame is selected, a dialog will appear for you to choose a frame. Use the panel on the left of the dialog to select a frame category. When a category is selected, a list of frame images will be displayed in the center of the dialog. Click on any image in the list to see a preview of the frame on the right side of the dialog.
When you find a frame you like, click the Download button. Once the image has finished loading, the frame image will be added to the project as a frame layer.