var pageSettings = {
  red: 200,
  green: 200,
  blue: 200,
  background : ['https://pictures.s3.yandex.net/background.jpg',
               'https://pictures.s3.yandex.net/cover-color.jpg',
                'https://pictures.s3.yandex.net/cover-grid.jpg',
                'https://pictures.s3.yandex.net/cover-typo.jpg',
                 'https://pictures.s3.yandex.net/cover-wall.jpg'
               ]
};

var bgColor = 'rgb(' + pageSettings.red + ', ' + pageSettings.green + ', ' + pageSettings.blue + ')';
document.body.style.backgroundColor = bgColor;

var header = document.getElementById('main-header');
header.style.backgroundImage = 'url(' + pageSettings.background[2] + ')';
console.log(header);