Make sure you're in the root directory of your application, then use:
npm run start
Your browser should open to http://localhost:3000 and you should see your Login screen.
Login screen of your Frigg app
Before you continue, make sure that both your frontend and backend are running. An easy way to know is to check if your terminal looks something like this:
The terminal output shows the backend server running locally, with a list of active routes and endpoints available for testing and development
If your terminal shows that the backend is also running, you can now experience with your app as an end-user and connect it to see live data coming through!