Please access to link https://code.earthengine.google.com/ to webpage in Google Chrome.

1. Create a variable representing (ee.Image) object a Landsat8 imagery
Select copy and paste the code below into webpage Code Editor.

var image = ee.Image(landsat8
.filterBounds(studyarea)
.filterDate('20140601', '20160901')
.sort('CLOUD_COVER')
.first());

var trueColor = {bands: ['B6', 'B5', 'B4'], min: 0, max: 0.3};
Map.addLayer(image, trueColor, 'Image_San_Francisco');

var ndvi = image.normalizedDifference(['B5', 'B4']);
var vegPalette = ['3b09d0','171dea','1916f4','ddeec9','13d622','07850b']
Map.addLayer(ndvi, {min: 1, max: 1, palette: vegPalette}, 'NDVI');