Although it is irregular, the preterite tense of estar is very similar to the preterite of the verb tener. The only thing you must do is to add es to the beginning of the verb.
El año pasado estuve en México Last year I was in Mexico ¿Dónde estuviste ayer? Where were you yesterday? Manolo estuvo ayer aquí Manolo was here yesterday El sábado estuvimos con We were with Juan on
Juan Saturday ¿Dónde estuvisteis el Where were you on Sunday?