On your Windows 8 or RT device, you launch the 'Store' application from the devices Start screen. You can then 'Search' for "TPControl" using the 'Search for apps' field.

Alternately, click the following link, available also on our Downloads page, which will launch the 'Store' application and take you to the TPControl app-page. From there you can install TPControl.
http://apps.microsoft.com/windows/en-GB/app/tpcontrol/ee1100ec-9caa-4977-8289-508ecdac89fa