Add app.js

app.js

@@ -0,0 +1,17 @@
+// app.js
+const express = require('express');
+const bodyParser = require('body-parser');
+const userRouter = require('./routes/users.route');
+
+const app = express();
+app.use(bodyParser.json());
+app.use('/users', userRouter);
+
+app.get('/', (req, res) => {
+  res.send('Hello World!');
+});
+
+const PORT = process.env.PORT || 3000;
+app.listen(PORT, () => {
+  console.log(`Server is running on port ${PORT}`);
+});