How to update iPad2 4.3.5 to IOS 5?

Connnect to iTune and tap on Check for Update button

http://i1224.photobucket.com/albums/ee374/Diavonex/154da938.jpg

Backup before you update

http://support.apple.com/kb/HT1766

See

iOS 5: Updating your device to iOS 5

http://support.apple.com/kb/HT4972

iOS: How to update your iPhone, iPad, or iPod touch

http://support.apple.com/kb/HT4623

If you are currently running an iOS lower than 5.0, connect to your computer & click on the "Update your device using iTunes".

Tip - You may need to disable your firewall and anitvirus software temporarily. Then download and install the iOS update. After you update to iOS 5.x, the next update can be installed via wifi (i.e., not connected to your computer).

 Cheers, Tom 😉