Create a new view.
Give the view a name
Show CiviCRM Participants
Create a page view perhaps, make sure there is a path
Add some fields, maybe you want the contact display name for instance
The custom field will be available in a group "CiviCRM Custom [custom_group_name]"
Add your custom fields...
Maybe you want only those participants for a given event?
Number of ways to do this, but lets just describe one way.
so lets say your View is at path "/event-participant-listing"
Lets use a contextual filter, and filter by event id, so that
"/event-participant-listing/1" would list participants for event with id 1
editing your view, Click the Advanced fieldset in the right column
Add a contextual filter
"CiviCRM Events: Event ID"
Maybe set "When the filter value is NOT in the URL" to 'Display contents of "No results found"'
Make sure if you choose that to add a "Global: Text Area" to the "No Results Behavior"