(1) When an action happened in the past, we can use "Simple Past Tense".
For example 例如:
I went to the cinema yesterday.
My mum took me to the Disneyland last week.

(2) Usually we see the words "yesterday", "last night", "last week", "last month", "an hour ago", this means the action happened in the past and we can use "Simple Past Tense".
通常如果我們在一句句子裡看見「yesterday」、「last night」、「last week」、「last month」、「an hour ago」等這些字時,就表示句子裡的動作是在過去的時間發生的,那我們便會用「簡單過去式」。

(3) To write the verb in "Simple Past Tense", for some words we can add "ed" at the end of it.
For example 例如:
added, explained, helped, moved, saved, used, agreed, attended, filled, completed, enjoyed, decided, etc.

(4) Sometimes, for some verbs, we need to change the whole verb into another word in order to change it into its past form, instead of adding "ed" at the end.
有一些動詞的過去式,不是把 "ed"加在最尾,而是會改為另一個拼法的字。
Examples 例子:
is / am > was
are > were
will > would
do > did
go > went

(5) Sometimes, some verbs have the same spelling for its "Simple Past Tense" form.
For example 例如:
read > read
put > put
cut > cut

Note: What is the past form of a verb? For most of the verbs, you just have to add "ed" at the end to change it into its past form. For the others (i.e. irregular verbs), you may look up in your dictionary or check it out in this link.
想知道某動詞的過去式是甚麼?大部分動詞的過去式只是在動詞的最尾加上 "ed",至於其他(即不規則動詞),你可查一下你的字典或按此瀏覽

(6) How to form questions and negative sentences in "Simple Past Tense"?

Did you go to the cinema yesterday?
Did your mum take you to the Disneyland last week?
Negative sentences:
I did not go to the cinema yesterday.
My mum did not take me to the Disneyland last week.

(1) = Simple Present Tense 簡單現在式
(2) = Simple Past Tense 簡單過去式

(1) Tom is always late for school.
(2) Tom was late this morning.

(1) We go to the toy library every week.
(2) We went to the toy library two days ago.

(1) I have my hair cut once a month.
(2) I had my hair cut last month.

(1) James often works until midnight on Fridays.
(2) James worked until midnight last Friday.

(1) Do you have a car? / Does Mary have a car?
(2) Did you have a car when you lived in Canada? / Did Mary have a car when she lived in Canada?

(1) I do not sing pop songs. / Linda does not sing pop songs.
(2) I did not sing pop songs a year ago. / Linda did not sing pop songs a year ago.

(1) Is your dad an engineer?
(2) Was your dad an engineer five years ago?

(1) Where does Kenny usually buy his clothes?
(2) Where did Kenny buy this shirt last week?

Examples of verbs in "Simple Past Tense" form (irregular verbs):
動詞簡單過去式的例子 (不規則動詞變化):

buy (買) > bought
eat (吃) > ate
drink (喝) > drank
draw (畫) > drew
forget (忘記) > forgot
feel (覺得) > felt
find (找) > found
has (擁有) / have > had
know (知道) > knew
see (看見) > saw
sing (唱) > sang
think (想) > thought
write (寫) > wrote

We need to read more to memorize the forms of the verbs in "Simple Past Tense".