Add -면 to a vowel-final stem or -으면 to a consonant-final one for "if/when", and end the result clause with -(으)ㄹ 거예요 to say what you will do. Korean has no separate future tense ending like English "will" - -(으)ㄹ 거예요 is literally "it is a thing to do".
Examples
- 시간이 있으면 여행을 갈 거예요.
- If I have time, I'll go travelling.
- 내일 비가 오면 집에 있을 거예요.
- If it rains tomorrow, I'll stay home.
- 돈이 많으면 좋겠어요.
- I wish I had a lot of money.
The mistake to avoid
Putting a future ending inside the 면 clause (있을 거면) - the condition stays in the plain present: 있으면.
Where this fits in
계획과 가정, Korean B1: Talk about the future, express wishes, and use hypothetical -면 constructions.