I confuse about be and verb" be(is am are) "

[mooyong]

I read in english grammar book I very confuse about be and verb" be(is am are) ".

In the book write we use I want you to be happy (Not I want that you are happy)

I confuse all the time about "be" when I should "be" and when i should use " Is am are" whom know that plases explain me

Thank you

[emsr2d2]

I read in english grammar book I very confuse about be and verb" be(is am are) ".

In the book write we use I want you to be happy (Not I want that you are happy)

I confuse all the time about "be" when I should "be" and when i should use " Is am are" whom know that plases explain me

Thank you

There are many occasions when you need the infinitive, but in the specific case that you quoted, it's simply because we don't say "I want that...", we say "I want + infinitive"

I want to be happy.
I want to buy shoes.
He wants to be thin.
She wants to have lunch.
They want to go to the cinema.

When you want something for someone else, or you want to do something, we simply add the extra word:

I want you to be happy.
I want her to buy shoes.
He wants them to be thin.
She wants him to have lunch.
They want us to go to the cinema.