Visit https://developer.foursquare.com/
Create new app on Foursquare.
You will required to Log in to Foursquare app. Incase you don't have Foursquare account then you need to register one before you can create new app.
Note: We have used localhost url so that we can test the application locally. When we are ready to go in production, we can change this url to production site url.