How to use new filters

Hi,
you can use them like this

add_filter( "adverts_manage_query", function( $args ) {
  // customize $args here
  // $args is an array of params that will be passed to WP_Query
  // https://developer.wordpress.org/reference/classes/wp_query/
  return $args;
} );
add_filter( "adverts_flash_data", function( $flash ) {
  // $customize $flash messages here
  return $flash;
} );

There is no one specific way to use as these are filters that allows extending the WPAdverts functionality, but you should rather first have some idea you would like to implement and then look at the filters usage on its own the filters are not that useful.