Back up your iPad. In most cases, updating the iOS will not cause a loss of data, but things can occasionally go wrong.
Connect your iPad to a power source. Use the charging cable that came with your iPad to connect to a power outlet or desktop computer.
Connect to Wi-Fi. Larger iOS updates require your iPad to be connected to a Wi-Fi network in order to download.
Open your iPad's Settings
Scroll down and tap General.
Tap Software Update. It's near the top of the page.
Tap Download and Install.
Enter your iPad's passcode and review Apple’s Terms and Conditions
Tap Agree. The download and installation process will begin.
Follow any on-screen prompts to restart your iPad.