- Redsn0w 0.9.8b4 only supports a tethered jailbreak, which means that you need to connect your iOS device to the computer on every reboot.
- If you've jailbroken your iPhone then you can use jailbreak apps such as AptBackup, PkgBackup or xBackup from Cydia to take a backup of all the jailbreak apps and tweaks so you can reinstall them easily after successfully jailbreaking your iPhone rather then installing them individually.
- Redsn0w 0.9.8b4 doesn't support iPad 2.
To learn the step by step procedure, visit this blog post How To Jailbreak iPad 1 Using Redsn0w For iOS 4.3.5 [Windows / Mac].
From Iphone Hacks