You can change the appearance of the main viewing area. For example, you can change the background color, select whether photos are displayed with a drop shadow or in a frame, and change the size of the text in your Source list.
To change the photo viewing area:
Choose iPhoto > Preferences, and then click Appearance.
Do any of the following:
To set whether photos are displayed in a frame or with a drop shadow, select the Outline or “Drop shadow” checkbox.
To change the background color, drag the Background slider.
To make the reflection of the Event’s key photo appear below the Event, select “Show reflections.”
To show the date, title, or ratings over your photos as you scroll through them in Events or Photos view, select the “Show informational overlays” checkbox. By default, the overlay shows the month and year the photos were taken as you scroll through them.
You can change the display to show the title or rating by choosing View > Sort Photos > By Title (or By Rating).
To change the size of the text in your Source list, choose a size from the Source Text pop-up menu.