We use these verbs to talk about necessity.
Present simple (Lesson 19)
He has to work nine hours a day, but he doesn't have to work very hard.
Let's stop. We don't need to finish today.
Past simple (Lesson 21)
Did they have to go out?
Yes, they had to go to the airport.
I needed to buy a number of things, but I didn't have enough money.
Present perfect (Lesson 24)
She has had to stay behind to look after the children.
With modal verbs (Lesson 27)
I may have to go to Winnipeg soon.
If she takes that job, they will need to move to another city.
NOTICE: We always use base form (Lesson 14) after to. We say he had to go (NOT he had to went).
EXAMPLE: We needn't finish today.
Students don't usually have to pay tax.
You need to get a visa before you travel.
I have to finish this report today.
We can't find a babysitter; we'll have to stay in tonight.
You needn't write it now. You can do it later.
There were no buses. I had to get a taxi.
He said that they had to go.