How to add Upload File Function in WordPress

I’m trying to create a plugin in which I want the option of uploading pdf document file. My code is as follows:

How can I proceed further? What function should I use in register_setting and how do I use file_upload function

class pdfPlugin {
    function __construct() {
        add_action( 'admin_menu', array($this, 'pdfPlugin'));
        add_action( 'admin_init', array($this, 'settings'));
    }

    function settings() {
        add_settings_section( 'pdf-first-section', null, null, 'pdf-plugin-settings');

        add_settings_field( 'document_name', 'Document Name', array($this, 'docHTML'), 'pdf-plugin-settings', 'pdf-first-section');
        register_setting( 'pdf_plugin_group', 'document_name', array('sanitize_callback' => 'sanitize_text_field', 'default' => 'My Document'));

        add_settings_field( 'pdf_upload', 'Upload PDF', array($this, 'uploadHTML'), 'pdf-plugin-settings', 'pdf-first-section');
        register_setting( 'pdf_plugin_group', 'pdf_upload', array($this, 'pdfUploadFile'));
    }

    function docHTML() { ?>
        <input type="text" name="document_name" value="<?php echo esc_attr(get_option('document_name'))?>">
    <?php   }

    function pdfPlugin() {
        add_options_page( 'Pdf Plugin Settings', 'Pdf Plugin', 'manage_options', 'pdf-plugin-settings', array($this, 'pluginHTML'));
    }

    function pluginHTML() { ?>
        <div class="wrap">
            <h1>PDF Plugin Settings Page</h1>
            <form action="options.php" method="POST">
                <?php
                    settings_fields( 'pdf_plugin_group' );
                    do_settings_sections( 'pdf-plugin-settings' );
                    submit_button();
                ?>
            </form>
        </div>
    <?php   }
}

$PdfPlugin = new pdfPlugin();