CREATE EVENT CUSTOM FIELD
To create a Custom Field, you'll go to Settings > Event Settings > Custom Fields. From there, you can select the Category: this is going to determine where this custom field will appear (if you are wanting players to complete this information, make it an Event Registrant custom field).
Select Category: this determines where the Custom Field will appear (if you are wanting players registering to an event to complete this information, make the custom field Event Registrant).
Field Type: This determines if the custom field is going to be a Text Area, Text Box, or Drop-Down Menu.
Label: This is what you want the Custom Field to be called/what you want the users to see when completing the Custom Field.
'Is Required': If you want this custom field to be optional (information may not apply to some users) then you can leave this unchecked.
REPORTING FOR EVENT CUSTOM FIELD
We'll go to Reports > Events > Registrant Detail. From there, just scroll down on the report until you see your custom fields at the very bottom.