Q: how i can upgrade software iOS 10 on my iPad version 8.1.2?

Go to settings, general, software update and check there. Or, connect to iTunes on your computer and update there. Are you having problems updating?

Note that not all iPads can support the update. This http://www.apple.com/ios/ios-10/ has a list at the end of the page.

Since you have a version of iOS that is 2 steps behind I suspect that you might have neglected to regularly backup your iPad. To prevent data loss should something go wrong with the update you should backup your iPad. The easiest way to do this is to connect your iPad to your computer running the latest version of iTunes.

1. Connect your iPad to the computer and in the menu of iTunes select File > Device > Your iPad > Transfer Purchases. This will backup any apps and other purchases to iTunes on the computer.

2. Then select the iPad symbol at the top of the iTunes window.

3. Select to backup your iPad. Choosing an encrypted backup will also backup passwords and other sensitive data. Do not forget the password you set there.

4. In the upper part of the iTunes window you should see an option to Update your iPad. After the backup has completed select Update and follow the prompts.