Were you doing the update via wifi or with the iPad connected to your computer? What iOs is currently on the iPad?
If you have an iPad 1, the max iOS is 5.1.1. For newer iPads, the current iOS is 6.1. 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).
after updating to the new 6.1 i wifi is going on and off. there were a few articles attempting to fix the issue. hard restart and resetting network setting. neither worked for me. what is going on! its bad on my 5 and even worse on by 4. this is completely unacceptable especially if hit that data cap from my provider. anyone have a good answer as to what is going on here. i need to also throw in in case apple is monitoring. My baby monitor is wifi so i have a serious issue with no baby monitor. angy is being nice here