plug in backend DB

package.json

@@ -24,6 +24,11 @@
     "webpack-dev-server": "^4.6.0"
   },
   "dependencies": {
+    "body-parser": "^1.19.1",
+    "cors": "^2.8.5",
+    "express": "^4.17.1",
+    "mongoose": "^6.1.1",
+    "nodemon": "^2.0.15",
     "react": "^17.0.2",
     "react-dom": "^17.0.2"
   }