Post types form

Hello

I hope everyone have a wonderful weekend.

To my problem, I have create a plugin to manage users to add cars to there owns porfile.
But I have a little problem.

1, to make a select to the form that show the options in types, now i have:

<select size="1" name="wpcf-carbrands">
<option value="<?php $carbrands=get_post_meta($post->ID, 'wpcf-carbrands', true); echo $carbrands; ?>"><?php $carbrands=get_post_meta($post->ID, 'wpcf-carbrands', true); echo $carbrands; ?></option>
</select>

2, to add the custom types in to the database, I have use the title and content to make it work, but need to change it to custom types.

function load_post_form() {
  $post_id = $this->get_post_id();
  $default = array(
      'title' => $_POST['bp_simple_post_title'],
      'content' => $_POST['bp_simple_post_text']
);
if (!empty($post_id)) {
   //should we check if current user can edit this post ?
   $post = get_post($post_id);
   $args = array('title' => $post->post_title,
       'content' => $post->post_content);
   $default = wp_parse_args($args, $default);
}

I hope someone can help me….