How can I create a custom endpoint for wordpress RESTAPI to "POST" data to the database?

See more:

REST

API

WordPress

Is there any documentation for it?
I've found lots of tutorials for "GET", but I can't find anything for "POST"

What I have tried:

For example to get data from database I use these codes:

add_action( 'rest_api_init', 'myfunction_name' );
function myfunction_name() {
register_rest_field( 
    'endpoint_name', 
    'field_name',
    array(
        'get_callback'    => 'get_data',
        'update_callback' => null,
        'schema'          => null,
         )
    );
}

function get_data() {
  $my_array = get_post_meta(
    15,
	"db_column",
	false
  );
return $my_array;
}

Now I want to create an endpoint and POST data to database with that.