You can change the color of the background used a Terminal window using Terminal preferences.
Choose Terminal > Preferences and click Settings.
Click Window.
Select a setting to modify from the Settings list, located on the left side of the Settings pane.
In the Background section, click the Color button.
Select a color from the color palette and close the palette window.
To be easily read, the color of the text and background should be chosen with a high degree of contrast against each other.