"Yesterday we had dinner in a new restaurant."
Translation:Ayer cenamos en un restaurante nuevo.
As I understand it, cenamos means "we dine" (dinner). Past tense of -amos should be -imos as i understand it. I speak Mexican spanish.
It comes from the verb Cenar - to have dinner.
Cenamos - we have dinner
Cenamos - we had dinner
Cenamos is the same word for present and past tense.
It's an -ar verb and does not conjugate to -imos in preterite, but -amos.