Use the Terminal application (typically in the Applications/Utilities folder). Use the "cd" command to change directories to the sample folder. For example:

cd ~/Development/Android/vuforia-sdk-android-1-5-9/samples/ImageTargets

You can run "ndk-build" from there. If the Android NDK folder isn't on your PATH you can run the command using the full path:

~/Development/Android/android-ndk-r7/ndk-build

(Note your ndk folder might have a different version number)

- Kim