Your username is by default your email address. When it does not seem to work than you have probably amended your username in the past.
You can ask a colleague to log-in to Negometrix and navigate to Company (menu in the right) and then the tab: 'Employees'. In the second column your username is displayed.
No colleague who can log in?
Contact the Negometrix Service Desk at 085-20 84 666 or email@example.com.