initial configuration with ui library and navigation

App.js

@@ -1,21 +1,21 @@
-import { StatusBar } from 'expo-status-bar';
-import React from 'react';
+import 'react-native-gesture-handler';
+import * as React from 'react';
+import { NavigationContainer } from '@react-navigation/native';
+import { createStackNavigator } from '@react-navigation/stack';
+
+import SignIn from './SignIn.js';
+
 import { StyleSheet, Text, View } from 'react-native';
+import { StatusBar } from 'expo-status-bar';
+
+const Stack = createStackNavigator();
 
 export default function App() {
   return (
-    <View style={styles.container}>
-      <Text>Open up App.js to start working on your app!</Text>
-      <StatusBar style="auto" />
-    </View>
+    <NavigationContainer>
+      <Stack.Navigator>
+        <Stack.Screen name="SignIn" component={SignIn} />
+      </Stack.Navigator>
+    </NavigationContainer>
   );
 }
-
-const styles = StyleSheet.create({
-  container: {
-    flex: 1,
-    backgroundColor: '#fff',
-    alignItems: 'center',
-    justifyContent: 'center',
-  },
-});