Step 1: find an image. I recommend a light size image. I have used this:
Step 2:
sudo cp /path/to/image.png /boot/grub/image.png
Step3: Edit GRUB as following:
sudo nano /etc/default/grub
and add:
GRUB_BACKGROUND="/boot/grub/image.png"
Step 4: update grub
sudo update-grub
Step 5: Reboot and enjoy 🙂
