In order to login to the website, click on the login button in the right top of screen of your desktop machine or in the middle top of the screen if you are on your mobile device. After which you will be taken to the login page where you will be presented with the following screen:

Enter your name and password and press login to continue. On succes you will either be logged in or if two-factor authentication has been enabled you will see the following screen:

Open up your Google Authenticator or Microsoft Authenticator and enter the code that's under the name of the website. If you enter the right code but the login still fails check the time on your Phone and Desktop machine to see if they match. If you do not have the code on your authenticator you need to mail an administrator to reset you Two Factor authentication.