Help me update my iOS please

Just follow the steps below or the ones in the link:

1. Plug your device into power and connect to the internet with Wi-Fi.
2. Go to Settings > General, then tap Software Update.
3. If you see more than one software update option available, choose the one that you want to install.

Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.

Update your iPhone or iPad - Apple Support (MY)

You also need to turn off Low Power Mode before you can perform the update.