Will and won’t are used to talk about the future. Will is positive and won’t is negative.
I will be late tomorrow.
John won’t be at the party next Saturday.

Use will and won’t to:
a) Make predictions.
In the year 2050, people will live under the sea.

b) Make an offer or promise.
I’ll buy you a drink.
John will help you with that box.

c) Make a decision about the future at the same time as you speak.
Sorry, we don’t have any tea.
That’s OK, I’ll have coffee.

1)  Will is the same for all persons.
I will go, you will go, he / she will go, we will go, they will go.

2)  Always write a verb in the infinitive form after will.
You will happy when you hear the news.     => You will be happy when you hear the news.

3)  You can contract will to ‘ll for pronouns.
I’ll buy it.     We’ll be late. 
He’ll be late home today.    They’ll be delighted.

But don’t contract will with names.
Mark’ll be late.     => Mark will be late.

4)  To write questions, write will before the subject.
Will you buy me a drink?
Will Tom get the job?

5)  The short answer for Will questions is: Yes, I/you/he/she/he/they/we will 
No, I/you/he/she/he/they/we won’t.
Do not contract will in short answers. 

Will John be late?
Yes, he’ll.=> Yes, he will.