Summarize:

It's usually at the bottom-left corner of the desktop. This opens the app. It's near the top-left corner of the app. It's near the bottom of the left column. It's next to "Office Updates" below the red "Office" header. A menu will expand. Windows will now check for updates to Microsoft Office. If updates are found, they'll be automatically installed in the background.
Click . Click All Apps. Click any app in the "Microsoft Office" groups. Click the File menu. Click Account. Click Update Options. Click Update Now.