To use the manager simply navigate to index.html in a web browser. You're directed to the main users page where you'll see a list of users imported from a JSON file. You can navigate to the groups page in the upper right corner and edit individual groups from that page.
To add a user click the 'Add user' button, fill out any of the fields, and click "Done" on the left side of the row.
To add a user to a group go to the 'Groups' page, click 'Edit' for any group, click 'Add user', select an existing user from the dropdown, and click 'Done'.
For development first clone the directory locally and run npm install.
If you'd like to use the development bundle just edit the script in index.html to use 'http://localhost:8080/dev.js' instead of 'dist/prod.js' and start the webpack-dev-server by running npm run dev
If you'd like to run the unit tests just run npm test.
All the test data is imported as JSON files inside the app but it could be easily configured to use an endpoint insead. In this case some likely endpoints would be "/api/users" and "/api/groups" which would return JSON for the app.
Check out the live version at https://coreymartin.github.io/User-Manager/