To add a picture to your Android home screen, you can follow these steps:
1. Open your device's Settings app and tap on Wallpaper or Display.
2. Select Set wallpaper and choose one of the available options.
3. If you'd like to use a photo from your Gallery, select the Photos option, then choose an image from the albums displayed in the Gallery app.
4. Once you've selected an image, confirm that you want to set it as your wallpaper by tapping Set Wallpaper or Apply at the bottom of the screen.
5. Your selected image will now appear as your home screen background!
It's also possible to download custom wallpapers from apps like Google Photos, Pexels and Pixabay for free!