To download PCalc, simply search for the word "PCalc" on your Apple TV. It's now free!
Select the icon for the app that appears, and it should take you directly to the App Store page.
If you have an existing App Store account, it's pretty much a one-click purchase. The application will download and install automatically and the store will keep you up-to-date when we have any new versions out.
Thanks for supporting indie developers in general, and our company in particular.