Add a normal text widget.

Enter the following code:

<div id="google_translate_element"></div><script type="text/javascript">function googleTranslateElementInit() {

 new google.translate.TranslateElement({pageLanguage: 'es', includedLanguages: 'de,en,es,fr,it,pt,ca,eu,gl', layout: google.translate.TranslateElement.InlineLayout.SIMPLE}, 'google_translate_element');

}

</script><script type="text/javascript" src="//translate.google.com/translate_a/element.js?cb=googleTranslateElementInit"></script>

Where do you put:

{pageLanguage: 'es', includedLanguages: 'de,en,es,fr,it,pt,ca,eu,gl',

you put the code of your base language (in my case it is 'es')and the comma separated list of languages you want to display in the drop-down.

List of available languages

https://cloud.google.com/translate/docs/languages?hl=es-419

Result: