After you backup.
If you have an iPad 1, the max iOS is 5.1.1. For newer iPads, the current iOS is 6.0.1. For the iPad Mini the iOS is 6.0.2. The Settings>General>Software Update only appears if you have iOS 5.0 or higher currently installed.
iOS 5: Updating your device to iOS 5 or Later
How to install iOS 6
iOS: How to update your iPhone, iPad, or iPod touch
If you are currently running an iOS lower than 5.0, connect the iPad to the computer, open iTunes. Then select the iPad under the Devices heading on the left, click on the Summary tab and then click on Check for Update.
Tip - If connected to your computer, you may need to disable your firewall and anitvirus software temporarily. Then download and install the iOS update. Be sure and backup your iPad before the iOS update. After you update an iPad (except iPad 1) to iOS 6.x, the next update can be installed via wifi (i.e., not connected to your computer).
A manual back-up via iTunes is not possible. When I connect my iPad 2 to my computer, iTunes (the latest version) only gives me the option to configure a "new iPad" or restore it using a prior back-up (my computer or iPhone). If I ignore this screen (click Done), the iPad is not listed or available for selection in iTunes.
Because I have 4.3.3 iOS, my iPad does not have iCloud installed or the ability to do a back-up via iCloud.
Bottom line, I can't back-up via iTunes or iCloud.
Is there a way to back-up my iPad without using iTunes or iCloud? I would like to carry forward my app purchases and other data when updating my iPad to iOS 6.
Thank you for trying to assist me.
Merry Christmas and Happy New Year!