WordPress.org

1. Download, unzip and upload to your WordPress plugins directory
2. Activate the plugin within you WordPress Administration Backend
3. Go to Post > Fields and add sidebar and drag and drop a "field" like widget for add field. The menu Taxo field is to manage field in taxonomies (in edit page).

To use in your theme, you can use next functions:

get_fieldmeta( $post_id = null, $name = null, $alone = true) : for post_type get_fieldmeta_taxo( $term_id = null, $taxonomy = null, $name = null, $alone = true ) : for taxonomy