Create custom post type

WpCustomPost.php

<?php
/**
 * Participant class
 */

class Participant
{
    public function __construct()
    {
        // Register post type with WP
        add_action('init', [$this, 'addPostType']);
    }

    public function addPostType()
    {
        $labels = [
            'name' => _x('Participants', 'post type general name'),
            'singular_name' => _x('Participant', 'post type singular name'),
            'add_new' => _x('Add New', 'Participant'),
            'add_new_item' => __('Add New Participant'),
            'edit_item' => __('Edit Participant'),
            'new_item' => __('New Participant'),
            'all_items' => __('All Participants'),
            'view_item' => __('View Participant'),
            'search_items' => __('Search participants'),
            'not_found' => __('No participants found'),
            'not_found_in_trash' => __('No participants found in the Trash'),
            'parent_item_colon' => '',
            'menu_name' => 'Participants'
        ];

        $args = array(
            'labels' => $labels,
            'description' => 'Participants description',
            'public' => true,
            'menu_position' => 3,
            'supports' => array('title'),
            'has_archive' => true,
        );

        register_post_type('participant', $args);
    }
}