You can install the Cydia demonstration for any iOS version using this Online Cydia Installer. Cydia demonstration allows you to jailbreak your iPhone, iPad or iPod (up to iOS 8.4) and upgrade it to fully Cydia. Click the following "install now" button to install demo version of Cydia
You can upgrade the Cydia demo app to the fully Cydia after installing it.Cydia is the main 3rd party app manager for iOS. You can install more than 10,000 free awesome apps using the Cydia.