Background color of views (navigator, console, tasks etc) is set according to the desktop (system) settings. On Linux/GNome I changed System/Preferences/Appeareance to change this color.
Editor colors are set chaotically by different editors, search for background in eclipse preferences to find different options. One easy way to get beautiful dark (and not only dark) themes is to install Afae plugin, and then pick theme within its preferences (twilight theme is beautiful, for example) - again, eclipse prefs, Afae group. Of course this applies only when you edit with Afae.