Participation on Wooclap is anonymous by default, but if you'd like to know who sent in which answer to a specific question, or find out who asked a certain question through the message wall, you have two options.
First: Allow them to fill in their (first) name
Second: Activate the "Authentication"
By turning on the authentication, you will require participants to create an account using email, Facebook, LinkedIn, Google+ or even Moodle, depending on the login methods you allow (e.g. email logins only).