To view all player registrations, head over to Event's registration page. 

If you have defined registration questions, you will find a button for each under "Registration questions". By clicking on it, it's answer will be uploaded for each signed up player:

By clickin on "Accounting", you can see a detailed description of the monetary situation for the registration (how much they owe / they have paid / the total registration fee / the part of fee derived from the ticket / the part of fee derived from options):

By clicking the edit icon you can update the data for each registration, or you can add a new one by clicking on "Add new". 

To assign a character, input it's name in the "Character" field:

To cancel a registration, click on "Cancellation", mark the check, and submit the form. 

You can manage the cancelled registration of the Event's cancellation page: