We use the First Conditional to talk about future events that are likely to happen.
If we take John, he'll be really pleased.
If you give me some money, I'll pay you back tomorrow.
If they tell us they want it, we'll have to give it to them.
If Mary comes, she'll want to drive.
The 'if' clause can be used with different present forms.
If I go to New York again, I'll buy you a souvenir from the Empire State Building.
If he's feeling better, he'll come.
If she hasn't heard the bad news yet, I'll tell her.
The "future clause" can contain 'going to' or the future perfect as well as 'will'.
If I see him, I'm going to tell him exactly how angry I am.
If we don't get the contract, we'll have wasted a lot of time and money.
The "future clause" can also contain other modal verbs such as 'can' and 'must'.
If you go to New York, you must have the cheesecake in Lindy's.
If he comes, you can get a lift home with him.