With most verbs the past tense is formed by adding -ed:
  
Verb
Past tense
Call          Called
WantWanted
LikeLiked
 
Exceptions in spelling when adding -ed:
 
After a final -e only add -d:love – loved                                                     
Final consonant after a short, stressed vowel
or -l as a final consonant after a vowel is doubled:
admit – admitted
travel – travelled
-y after a consonant becomes -ihurry – hurried
 
But there are a lot of irregular past tenses in English. Here are some examples of irregular verbs in English, with their past tenses:
 
Infinitive
Irregular past
be                  was/were
breakbroke
bringbrought
buybought
choosechose
costcost
gowent
havehad
 
The verb 'to be' is irregular in the past simple. There are two simple past forms: 'was' and 'were'. It also has different question forms and negative forms. Always remember that you do not use 'did' with the verb 'to be' in the simple past.
 
Positive
Negative
Question
I was.                               I was not. (I wasn't.)Was I?                             
You were.You were not. (You weren't.)Were you?
We were.We were not. (We weren't.)Were we?
They were.They were not. (They weren't.)Were they?
He was.He was not. (He wasn't.)Was he?
She was.She was not. (She wasn't.)Was she?
It was.It was not. (It wasn't.)Was it?
 
Modal verbs
  
'Must' becomes 'had to':
I must call my wife now. I had to call my wife yesterday.