If you’re applying an HD-optimized theme (Pro Edition), you’ll need to change the Page Setup for your presentation to the correct HD aspect ratio - slide layouts/elements will otherwise appear “squished” when applied to standard-definition files.

Apply the HD theme variation to your presentation, then click on File > Page Setup (Mac) or on the Design tab in the Ribbon, then Page Setup (Windows): change the “Slides sized for” setting to “On-screen show (16:9)” or “On-screen show (16:10)” depending on your type of display or projector - PowerPoint will resize your presentation to the correct HD format you’ve chosen.

If your theme package includes alternate color palettes, or if you’d like to apply the theme’s core color palette to another presentation, the theme color XML file(s) will need to be copied to the correct directory before they can be applied to a presentation. Locate the theme ZIP file you downloaded and extract the contents to a memorable location.

Mac

Open the extracted folder, and navigate into the Theme Colors folder - copy the enclosed color definition file(s) (.XML) to:

Applications / Microsoft Office 2008 / Office / Media / Templates / Office Themes / Theme Colors

Windows

Open the extracted folder, and navigate into the Theme Colors folder - copy the enclosed color definition file(s) (.XML) to:

Program Files \ Microsoft Office \ Document Themes 12 (or Document Themes 14 if you’re using the Office 2010 Beta) \ Theme Colors

This will integrate the color palette(s) into the theme Color selector: apply the color definitions to your presentation by clicking on the Colors selector in the Document Theme inspector (Mac) or by clicking on Design in the Ribbon and clicking the Colors button (Windows) - the new palettes will appear in alphabetical order, though you may need to restart PowerPoint before the new palettes appear in the selector.

We use iStockPhoto.com extensively for the sample stock photos shown on the site. iStockPhoto images are inexpensive, very good quality, and actively support independent photographers. We do not include photos as part of our theme packages for several reasons (ultimately, to do so would drive up the cost of the themes to the benefit of a relative few), but if you'd like to use one of the images you've seen on our site in your own presentation, we've made it easy.

Sign in to Your Account, and navigate to the Theme Library page for the theme in question - Stock Photo References, when available for Royalty-Free use, will be listed at the bottom of the page. iStockPhoto images are noted by name and hyperlinked.