Hi@akhtar,
You need to use the MaterialApp method to create an App. You can see the below example. It may help you.
import 'package:flutter/material.dart';
void main() {
var x = Text(
'Hello',
textDirection: TextDirection.ltr,
textAlign: TextAlign.center,
);
var design = MaterialApp(home: x);
runApp(design);
}