To set a background image for a screen in Flutter, you can use a Container or the decoration property of a Scaffold widget. Here's an example of using a Container as the background for a screen:

declare the asset in your pubspec.yaml file:

           flutter:
              assets:
                - assets/background_image.jpg

           

Main screen

           import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

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

class BackgroundImageScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        decoration: BoxDecoration(
          image: DecorationImage(
            image: AssetImage('assets/background_image.jpg'),
            fit: BoxFit.cover,
          ),
        ),
        child: Center(
          child: Text(
            'Your Content Here',
            style: TextStyle(
              fontSize: 24,
              color: Colors.white,
              fontWeight: FontWeight.bold,
            ),
          ),
        ),
      ),
    );
  }
}