In the sentence "<em>Alejandro </em><em>llevó </em><em>un sueter marrón", </em>the tense being used in the sentence is:
Preterite
The Preterite is a tense is used in Spanish to describe actions completed or finished at at point in the past. It should not be confused with the <em>Imperfect </em> which is used to talk about routines and habits in the past, ( just like "used to" in English)
Examples of Preterite:
Yo compré un carro nuevo el año pasado. ( I bought a new car last year)
This sentence refers to an action that happened at a specific moment in the past. The preterite is used as the simple past in English.
Http://www.dvusd.org/cms/lib011/AZ01901092/Centricity/Domain/4920/Washingtons%20farewell%20address.pdf
Read paragraph 3 .. its all of that