signed apk for android

Press on "BrowseKeystore" - it will let you pick new file for storing Keystore. Then press dropbox under Key->Alias and choose "Create new key". Select your key. That should allow you to make a build signed with your key.

If you're planning to sell your game/application on Android Marker, you probably want to sign it with LVL key. You get your LVL key from android.marker.com/publish (you need Android developer account). Enter LVL key into last field. This will sign your build with LVL, but you still need to check if application is valid inside of application and do something based on that. Read about iPhoneUtils.isApplicationGenuine - you need to call that in your application.