Use the first conditional to talk about possibilities, possible events, and probable results. Use simple in the if-clause and will/'ll or won't in the other clause.
What will they do if they win the game?
If they win the game, they'll have a big party.
They'll be very sad if they don't receive the trophy.
Use the first conditional to give warnings or make threats.
If you don't arrive by midnight, we'll lock the door.
If you say thet again, I'll scream.