To change your WhatsApp profile background, follow these steps:

1. Open WhatsApp on your mobile device.
2. Tap on the three dots in the top right corner of the screen to open the menu.
3. Tap on “Settings” from the menu.
4. Tap on “Chats” from the Settings menu.
5. Tap on “Wallpaper” from the Chats menu.
6. Here you will see several options to choose from, including solid colors, default backgrounds, and your phone’s gallery. You can select any of these options to choose a new background.
7. Once you’ve chosen a new background, you can preview it by tapping on it.
8. If you’re happy with the new background, tap on “Set” to save it.

Your new background will now be set as your WhatsApp profile background.