Click on Sign up for Foursquare and complete the steps to create your account.
When creating your app, use Cognitive Builder Faire SF for your app name and www.cognitivebuildersf.com for your application URL. Click Create a new app.
Copy and save your CLIENT_ID and CLIENT_SECRET to a place where they can be easily retrieved, but where they won’t be pushed to github. If you're not sure where to put them .bash_profile could be a good place.