Spanish language Q&A Forum

I would just like to request more examples for practice before this particular lesson gets to the Kwiz Questions. And thanks for adding the Latin America option!

"Aparecerás en el perfil de la búsqueda..."   "... tu disponibilidad y el país preferido..."  I included "la" with búsqueda and "el" with país, but are not used here.  I never really know when and when not  to use them.  Is there a lesson somewhere on the website about when to use the articles?  I forgot to add at the beginning when we are translating "As an au pair", the correct way is to say "Como au pair..." and again, I wrote "Como un au pair..."  This is another example of me being confused as to when and how to use the articles.

I just saw it in the forum and I think it should be added to the lesson since it is quite common. 

Él pudo irse de vacaciones

why we use 'irse' in this sentence? instead of 'ir'