<form method="post">
<input type="text" name="title" /> //Title
<input type="text" name="desc" /> //Description
<input type="text" name="age" /> //Age autor
</form>
This code add title and description in new article. But how do I add custom date? ex. age input.
$title = $_POST['title'];
$desc = $_POST['desc'];
$date = array(
'post_title' => $title,
'post_content' => $desc,
'post_status' => 'publish'
);
wp_insert_post($date);
look into custom meta boxes. Here is an excellent article about it http://wp.smashingmagazine.com/2011/10/04/create-custom-post-meta-boxes-wordpress/
The initial function that allows you to save custom fields is add_post_meta(). Example:
add_post_meta( $post_id, $meta_key, $new_meta_value, true );
You could do the following if custom meta boxes is not what you are looking for:
$post_ID = wp_insert_post($date);
add_post_meta( $post_ID, 'custom_field', 'content for custom field', true );
wp_insert_post will return an ID. You would then use that to add post meta.
https://codex.wordpress.org/Function_Reference/wp_insert_post https://codex.wordpress.org/Function_Reference/add_post_meta
E.g.
$id = wp_insert_post( $date );
$age = {GET AND SANITIZE YOUR AGE INPUT}
add_post_meta( $id, 'age', $age, true );
