$ npm i -g google-apps-script
$ gas new myProject && cd myProject
$ gas i -s sheet
$ gas push
Start by openinging your sheet by id
var MySpreadSheet = SpreadsheetApp.openById('my-spreadsheet-id-goes-here');
var Sheet1 = MySpreadSheet.getSheets()[0];
Retrieve the value from a given cell in a given sheet
sheet_getValue(row, column, sheet);
Set the value of a given cell in a given sheet
sheet_setValue(row, column, sheet, value);
Set cell the background color of a given cell in a given sheet
sheet_setBackgroundColor(row, column, sheet, backgroundcolor);
Set the font color of a given cell in a given sheet
sheet_setFontColor(row, column, sheet, fontcolor);