Where to add file-folder filter

On the export page, there is a recommendation to add the following code to filter out files, folders, and file types. In what file does this code need to be added?

// to exclude file/folder
add_filter(‘wt_mgdp_exclude_files’, ‘wt_mgdp_exclude_files_fn’);
function wt_mgdp_exclude_files_fn($arr)
{
$arr[]=’ai1wm-backups’; // add folder/file path relative to wp-content folder
return $arr;
}

// to exclude file types
add_filter(‘wt_mgdp_exclude_extensions’, ‘wt_mgdp_exclude_extensions_fn’);
function wt_mgdp_exclude_extensions_fn($arr)
{
$arr[]=’zip’;
$arr[]=’mp4′;
return $arr;
}