wordpress多语言po文件

i want to add 2 languages in my word press theme, i already have the translated .PO files ready but the theme uses only 1 of them,the default one. i tried to rename the desired language file from ar_EG.po to en_US.po which is my default language file and replaced it so that i can change my website language, it worked but i can't find anyway to make my website support 2 languages that people can switch from using a word press language plug-in.

Try to add this to your_theme_setup function in functions.php

load_theme_textdomain( 'your_theme_name', get_template_directory() . '/languages' );

$locale = get_locale();
$locale_file = get_template_directory() . "/languages/$locale.php";

if ( is_readable( $locale_file ) ) {
    require_once( $locale_file );
}