preterito perfecto and preterito indefinido

Hola Odette, 

The Pretérito Indefinido is often called the simple past in English. It is the tense used to describe an action that took place in the past, or to describe something that happened in the past, and that the action is fully completed and / or took place in a period that is completely over; for example “I went to Spain last year.”  “Fui a España el año pasado.” There is no doubt in this sentence that the action is fully completed, and the period concerned is definitely in the past.

Hope that helps. Saludos. John