CODE EXAMPLE FOR JAVASCRIPT

google sheet app script

function myFunction() {
  // SpreadsheetApp,Sheet,Range
 const ss=  SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Order')
 const rng= ss.getRange("A1:C1");
 rng.setBackground('green')
 rng.setFontWeight('bold')
 rng.setFontColor('white')
 
}