Cydia is a Jailbroken equivalent of App Store, and to get Cydia on iPhone 4S iOS 5, you will have to jailbreak your iPhone 4S. Jailbreaking your device will help you gain root access to the device in order to install unauthorized applications from Cydia.
This is necessary in some cases because Apple has very tough App Store policies and rejects some apps that you will find very useful. When your iPhone 4S is jailbroken, you will be able to download these unauthorized (but very useful) contents from Cydia and make your iPhone more exciting. Interestingly, Cydia does not prevent you from using App Store any other time you like.
Already, Pod2g and other iPhone hackers are working hard to come up with an untethered jailbreak solution to enable users get Cydia on iPhone 4S iOS 5. Pod2g, MuscleNerd, iPhone Dev Team and Planetbeing are all on the dream team looking for a path for the release of a jailbreak solution for iPhone 4S. Pod2g already has an untethered 4S, but it can’t be released publicly because the exploit he used to inject the untethering files to the phone relies on having a developer account.
If you are new to jailbreaking, you may have to be quite cautious in making changes to your iPhone. Before changing anything, always make sure your device is well backed up.
Presently, you can get Cydia on your iPhone 4S iOS 5 by purchasing the software from Unlock iPhone 4S or iPhone Unlock Easily. You simply have to purchase and download the software, and get a members-only password. You will be guided throughout the installation and jailbreaking process from start to finish, and both Windows and Mac are supported.
So, you have two options before you. You either have to wait till the dream team come up with free jailbreaking solution or grab a paid one from these sites in order to get Cydia on your iPhone 4S iOS 5.