Well, it depends on the app. Apple has developed the Mac App Store where you can use the apps (some full screen) on your computer. So, do a software update (if you haven't already) and click the App Store icon in your dock. (Or click the apple symbol and click Mac App Store.) Then search for your app and see if the app you wanted is there. PLEASE NOTE: This only works on Mac. If you have a PC, try to Google "Mac App Store download for Windows"
Hope This Helps,
OstriMonk