Choose a sticker maker app or use WhatsApp Web
Prepare images with transparent backgrounds
Crop the image to the desired shape
Remove the background if needed
Add text or decorations if desired
Save the image in PNG format
Open the sticker maker app
Create a new sticker pack
Add the prepared images to the pack
Export or publish the sticker pack to WhatsApp
Open WhatsApp
Go to the sticker section in a chat
Select and send your new stickers