How do I download ios5 or ios6?

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

You have to download and install via itunes on a computer. Your current iOS doesn't support updated directly from the device.

You have to do this using iTunes on a computer if you are using iOS 4 or earlier.

You need to connect your iPad to iTunes on your computer with the USB cable. First backup, then run the update option to get iOS 6.0.1

The over the air update feature only appeared with iOS 5, so until you update, you won't have it on your iPad.

You'll need to connect it to iTunes and update through there.

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

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

You may want to scroll down to the section titled: Update your device using iTunes