To use Foursquare Swarm, first sign up for a Foursquare account. Once you have an account, open the Foursquare app and sign in. On the left side of the app, click on the three lines in the top left corner. On the right side of the app, click on the three lines in the top right corner. Type in the four-digit code that you see in the top left corner of the app. The code will open a web page with more information about Foursquare Swarm.