Add Vendor Settings to admin dashboard

Thanks, but I’m not sure where / how to add that line in my custom plugin.
If I add it into the actual function being called, it doesn’t seem to do anything, if I add it outside, $vendor_id is not defined. This is what I have now:

function custom_store_settings( $vendor_id ) {
    global $WCFM, $WCFMu;
    $wcfm_vendor_custom_options = (array) get_user_meta( $vendor_id, 'wcfm_vendor_custom_options', true );
    $wcfm_vendor_desc_website = isset( $wcfm_vendor_custom_options['website'] ) ? $wcfm_vendor_custom_options['website'] : '';
    // some more fields here
?>
    <!-- collapsible -->
    <div class="page_collapsible" id="wcfm_settings_form_vendor_custom_head">
        <label class="fa fa-file-image-o"></label>
        <?php _e('Winery Images', 'wc-frontend-manager-ultimate'); ?><span></span>
    </div>
    <div class="wcfm-container">
        <div id="wcfm_settings_form_vendor_desc_expander" class="wcfm-content">
            <?php

            $WCFM->wcfm_fields->wcfm_generate_form_field( apply_filters( 'wcfmu_settings_fields_vendor_store_invoice', array(
                "wcfm_vendor_descr_website" => array('label' => __('Website', 'wc-frontend-manager-ultimate'), 'type' => 'text', 'name' => 'wcfm_vendor_custom_options[website]', 'class' => 'wcfm-text wcfm_ele', 'label_class' => 'wcfm_title wcfm_ele', 'value' => $wcfm_vendor_desc_website, 'hints' => __( 'Your website URL', 'wc-frontend-manager-ultimate' ) ),
                // more fields here
            ) ) );
            ?>
        </div>
    </div>
    <div class="wcfm_clearfix"></div>
    // More containers and fields here
    <!-- end collapsible -->
    <?php
}
add_action( 'end_wcfm_vendor_settings', 'custom_store_settings', 20 );

function custom_store_settings_update( $user_id, $wcfm_settings_form ) {
    global $WCFM, $WCFMu, $_POST;
    if( isset( $wcfm_settings_form['wcfm_vendor_custom_options'] ) ) {
        $wcfm_vendor_custom_options = $wcfm_settings_form['wcfm_vendor_custom_options'];
        update_user_meta( $user_id, 'wcfm_vendor_custom_options',  $wcfm_vendor_custom_options );
    }
}
add_action( 'wcfm_vendor_settings_update', 'custom_store_settings_update', 20, 2 );