Tap the Share button

The Share button looks like a box with an arrow pointing up ↑
It's at the bottom centre of Safari on iPhone,
or the top right on iPad.

Scroll down and tap "Add to Home Screen"

In the Share sheet that slides up, scroll down until you see
"Add to Home Screen" with a plus icon. Tap it.

Tap "Add" to confirm

A confirmation screen shows the app name and icon.
Tap "Add" in the top-right corner. Done.