Frontend(s) for multiple emulators that run on an Android device.
Files hosted at Google Play will have a "Get it at Google Play" icon located in the lower right hand corner. Simply click the Google Play icon.
With the exception of paid apps, clicking the "Download Now" icon will download the file to your Android device or computer.
Installing downloaded apps will require a "File Manager" such as ASTRO File Manager or ES File Manager. Simply download the file to your phone, tablet, etc. and use the File Manager to "browse" to the file and select. This will give you the option to install. You will also have to change security settings by checking the box next to "Unknown Sources - Allow installation of non-Market apps"