User Themes will reside in Keynote's Application Support folder. Place your themes in the following locations:

Themes that will be available to all users on the Mac: /Library/Application Support/Keynote/Themes/

(If you put the files under your user directory, other users will not have access to the themes.)
~/Library/Application Support/Keynote/Themes/

(Note: ~ in Mac OS X lingo means /Users/YourUserName/ )

Our premium themes come with an installer that installs all of the themes in /Library/Application Support/Keynote/Themes/. Simply run Keynote to access your new themes.

Our premium packages may also install extra graphics that are installed in the Keynote Graphics Library. Look under File>Open Image Library to view the graphics file.