The Apple Support Communities are an international user to user technical support forum. As a man from Mexico, Spanish is my native tongue. I do not speak English very well, however, I do write in English with the aid of the Mac OS X spelling and grammar checks. I also live in a culture perhaps very very different from your own. When offering advice in the ASC, my comments are not meant to be anything more than helpful and certainly not to be taken as insults.
Are you using the correct app store? If you are using the iTunes App Store, apps for iOS devices, then you need to switch to the Mac App Store, apps for Macs. The Mac App Store is the App Store app in your Mac's Applications folder. It can also be opened from the App Store selection in the Apple Menu. It also comes by default in the Dock.