Step 1: Create a image file to use as a sticker app.

Create a image file to use as a sticker app.
The sticker you want to make should be prepared as an image file.
The best way is to draw what you want with Photoshop.
But if you do not have the skill of painting like me, you can download it from the internet and use it.
However, doing so may result in copyright infringement.
So the image file you use should be commercially available.
(You can find it on a site similar to "https://pixabay.com." That's how I created the sticker app I created.)
Recently, my wife scanned hand-drawn images and used them.
If you do not have the ability to draw pictures on your computer or you do not have the equipment, this is a good way.
The picture below is what has been made recently.

Prepare various image files in your own way.

See previous post.
lets-make-stickers-and-icons-as-image.
https://www.smart4edu.com/2018/10/lets-make-stickers-and-icons-as-image.html