I can,t download ios 6 on my ipad??

More info please.

You tried to update through wifi on your phone or through iTunes? What did the error message say?

See

iOS 5: Updating your device to iOS 5 or Later

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

How to install iOS 6

http://www.macworld.com/article/2010061/hands-on-with-ios-6-installation.html

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

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

Tip - Be sure and backup your iPad before the iOS update.

 Cheers, Tom 😉