How to use contexual filters for registration events? I want to create a block on the side of the page that will show registered users to a event. I already have a event type and calendar system + a registration system. 

When a user registers for a event, I can get the view to display it. However, it is displaying literally ALL registration users for ALL events. I am trying to get the contextual filter to just narrow it down to the specific event, but cannot get it to work.

Any help?
You don't use contextual filter for this, you need to use relationship.

Make sure the Registration Views module is enabled.

In views under Advanced, RELATIONSHIP click add and select User: Registration


Checkmark require this relationship. 
Checkmark your registration type name.