Wah How to use "Will"

We can use "will" to talk about the future. We also use will to predict, to promise, to request, make a threat and talk about decision.

Affirmative           
    I will come back later. (I'll come back later.)
    He will come to the dinner. (He'll come to the dinner.)

Negative
    I will not come to the dinner. (I won't come to the dinner.) 
    I will not go away from you. (I won't go away from you.)

Interrogative
    Will you come to the party tonight?
    Will it rain this afternoon?         

1. We use will to talk about the future.
    I'll be back next two weeks.
    I'm in the meeting right now, I'll call you later.

2. We use will to make predictions.
    I think it'll snow tonight.
    I'm sure he'll be a successful manager one day.

Note: I don't think it'll snow tonight  I think it won't snow tonight. is incorrect.

3. We use will to make decisions.
    I'll have mushroom soup. (I would like to have mushroom soup)
    I'll go with you.
    I'm cold. I think I'll turn on the heater.

4. We use will to request, to promise and threat.
    Request: Will you give me some money?
    Promise: I'll help you with your work tomorrow.
    Threat:  If you don't tell me, I'll kill you.

"Near, far, wherever you are
I believe that the heart does go on
Once more you open the door
And you're here in my heart
And my heart will go on and on..."  from "Titanic" Soundtrack - Céline Dion