Three different types of conditional sentenses can be distinguished:
It refers to an action which will generally happen in the future (future possibility).
[if + present simple] + [future simple(will)]
If he finishes his homework, he’ll go to the cinema.
It refers to a hypothetical or imaginary situation in the present or future; also used to express advice, hope or ambition.
[if + past simple] + [conditional simple (would)]
If I met Leonardo DiCaprio, I’d ask him for his autograph.
It refers to an unfulfilled condition in the past which may be used to express regret about the past.
[if + past perfect simple] + [conditional perfect] (would have + participle )
If she had got up earlier, she wouldn’t have missed the train.