How to jailbreak my iPhone 4 version 5.1.1?

Please tell me how to jailbreak my iPhone 4
And after jailbreak what changes in my iPhone warntey
And how to recover all app and data of iPhone after jailbreak

I think you can't jailbreak iPhone yourself. You need to find a iPhone authorized technician to do that.

Simply follow the step so you can jailbreak your iPhone 4 version 5.1.1

http://iphonejailbreak-unlock.com

Please follow the steps to jailbreak the iphone:-

Step 1: Download Absinthe 2.0 from here.

Step 2: Once the tool has been downloaded, find the compressed file and extract all of the contents like you would with any standard zip file. Place the files on your desktop for easy and quick access.

Step 3: Using a standard 30-pin connector cable, connect the device to be jailbroken with your computer.

Step 4: Launch the Absinthe tool through the executable file which you downloaded in step 1. When launched, the program will show an initial interface that will have some text-based information on it, and a "Jailbreak" button.

Absinth2

Step 5: If the device is connected properly as per step 3 then the Jailbreak button should be available. Press the button to begin the jailbreak process.

The initial Absinthe tool for iOS 5.0.1 accompanied with it a new method for jailbreaking iOS devices, so with that in mind, don't be alarmed if the device looks like if it is going through a restore process. The progress bar on the Absinthe GUI will provide user feedback, please don't touch the device at this time.

Step 6: When the payload process is complete and you're confronted with your device's lock screen, the ever familiar Cydia icon will be present on the home screen. The device is now successfully jailbroken untethered and you can now install any extensions or packages via Cydia, provided that your device is supported by them.

After jailbroken your device will support all applications which r not included in istore due to their terms and conditions. You just does not follow the rules of apple after jailbroken.

their is no need to backup the data for jailbreaking. But for safrty purpose you can backup through your PC.
>Connect iphone to your pc.(hoping that itunes is insatlled on your pc)
>Just click on itunes icon and on left side click on backup and restore link.
>it will backup all your apps.