Starting with Google App Script

first-step-google-app-script.js

function doGet(request) {

  // get first page from current spreatsheet 
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = spreadsheet.getSheets()[0];
  
  var result = sheet.appendRow([
    "doGet",
    "sample"
  ]);
  
}

function doPost(request) {
  
  // get first page from current spreatsheet 
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = spreadsheet.getSheets()[0];
  
  var result = sheet.appendRow([
    "doPost",
    "sample"
  ]);
  
}