How do I get an icon back on my app screen?

[AC Question]

I was trying to adjust the placement of my icons on the app screen following the scanty instructions in the user guide. In so doing the icon for settings has vanished and I'd like to get it back.
The app is still on the phone but not on the app page.
I have a Galaxy J1 (2016)
Thanks.

 

[hallux]

Long-press it where you see it, then drag it to where you want it.