You can buy the app on Google Play (formerly known as the Android Market). Just start the “Market” app and search for “CalenGoo”. Or you can tap this link in your Android phone’s browser: CalenGoo Download
Normally you should buy the app in Google Play (the Android Market) as described above. Only if you you have problems, e.g. if you are from a country from which you cannot buy paid apps in the store or you don’t have a credit card or your credit card does not work with the Google Play Store, you can use AndroidPIT, Amazon or pdassi instead:
To buy it from AndroidPIT, follow these instructions: Use your Android browser and open http://www.androidpit.com. Then tap “Install App Center” to install an alternative store. Please see here for more installation instructions: AndroidPIT App Center
After you have installed “App Center”, use it to search, buy and download “CalenGoo”. You can pay using a credit card with “clickandbuy” or you can use PayPal to charge your account with money and pay this way.