Here's how you can spice the terminal application in OS X by adding a background image.
1. Open the terminal app.
2. Go to the Preferences menu.
3. Go to Settings.
4. Click the Window tab.
5. Click the Image drop down menu and then click Choose.
6. Add your image and it will appear in the terminal window.
For more, see the original article at the link below.
Adjust Background Opacity, Blur, & Background Image | OS X Daily