Below are the instructions for upgrading an iPad to the latest Operating System. Please follow all the steps and be sure to Back Up your iPad before proceeding.
Step 1 - Back up your iPad using iTunes
Make sure your computer has the latest version of iTunes.
Connect your iOS device to your computer.
Choose File > Devices > Back up.
Note: If you're using iTunes 10.7 or earlier, right-click the device from the list and choose Backup Now.
Step 2 - Upgrade to latest iOS
Option 1 - iTunes
Open iTunes (If not already installed on a PC, click the link for the installer)
Plug in iOS device into an open USB port on your computer or laptop.
In the upper left hand corner of the window, a silhouette of the device will appear
(Click on the icon if it does not come up automatically)
On the next window is the iOS devices configuration settings
(This is where you can backup your device and update it)
In the upper middle of the window it will tell you what iOS version you are currently on. (8.4, 9.1, etc)
(See Below) Mine says that I have a newer version of iPad software available.
iTunes will prompt you to accept the new terms of the software and will then download the software
Once the iPad restarts and your lock screen appears, you will be updated and iTunes should show that you are on the new software.
Option 2 - Wireless
Open Settings (Gray Gear Box)
On the left side: Go to General
On the right side: Go to Software Update
On this screen it will say one of the following:
Download and Install
Manage Storage (You do not have enough free space to do the update wirelessly.
Make sure the device is plugged in and run the update
Your device will restart at least once
Once your lock screen comes back on the update is complete