There are numerous ways to state the past tense in Portuguese. A few can be found below.
THE DEFINTE PAST: MOST POPULAR/USEFUL PAST TENSE FORM
The definite past is used when you are talking about an action that has taken place in the past and has stopped happening (this will make more sense after you watch the video about the imperfect). For examples,
I ate yesterday - Eu comi ontem. He ate last week – ele comeu a semana atras.
Each ending (ar, er, ir) have different endings in the definite past.
IRREGULARS IN THE DEFINATE PAST: SER IR ESTAR AND TER
Ser “to be” and Ir “to go” they have the same form… eu fui, tu foste, ele/ela/voce foi, nos fomos, voces/eles/elas foram.
Ter “to have” eu tive, tu tiveste, voce/ele/ela teve, nos tivemos, voces/eles/elas tiveram,
Estar “to be” eu estive, tu estiveste, voce/ele/ela teve, nos tivemos, voces/eles/elas tiveram.
THE IMPERFECT PAST TENSE:
The imperfect is used for continuous events in the past. For example, When I was young, I swam a lot - quando era pequeno, eu nadava muito.
AR verb endings for the imperfect. All you do is drop the -ar from the end and add the endings. (andar to walk) Eu andava, tu andavas, voce andava, ele andava, ela andava, nos andavamos, voces andavam, eles andavam, elas andavam.
ER and IR verbs share the same endings in the imperfect. Drop the ir/er and add “ia” and its extras. (comer – to eat) eu comia, tu comias, voce comia, ele comia, ela comia, nos comiamos, voces comiam, eles comiam, elas comiam.
There are more videos to come dealing with the past tense subjunctive, the “i have done” past tense, and much more.
