Navigator.push(
  context,
  MaterialPageRoute(builder: (context) => SecondPage()),
);

Navigator.pop(context);

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: FirstPage(),
    );
  }
}

class FirstPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("หน้าหลัก")),
      body: Center(
        child: ElevatedButton(
          child: Text("ไปหน้าถัดไป"),
          onPressed: () {
            Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => SecondPage()),
            );
          },
        ),
      ),
    );
  }
}

class SecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("หน้าที่สอง")),
      body: Center(
        child: ElevatedButton(
          child: Text("ย้อนกลับ"),
          onPressed: () {
            Navigator.pop(context);
          },
        ),
      ),
    );
  }
}