Apps script example.js

var ss = SpreadsheetApp.openById('Your spreadsheet id');

function doPost(e) {  
  var returnedData = {};

  // Retrieve and process any URL parameters, as necessary.
  var data = e.parameter.data;
  try {
    addRow(data);
    returnedData.result = 'OK';
  } catch (e) {
    returnedData.result = 'FAILED';
    returnedData.error = e.toString();
  }
  
  if (e.parameter.callback) {
    return ContentService.createTextOutput(
      e.parameter.callback + '(' + JSON.stringify(returnedData) + ');')
    .setMimeType(ContentService.MimeType.JAVASCRIPT);
  }
  
  return ContentService.createTextOutput(JSON.stringify(returnedData))
    .setMimeType(ContentService.MimeType.JSON);
}

function addRow(exampleData) {
  var sheet = ss.getSheetByName('TestSheet'),
      lastRow = sheet.getLastRow();
  
  sheet
    .getRange(lastRow + 1, 1, 1, 1 /* row count */)
    .setValues([[
      exampleData
    ]]);
}