Herobrine has never been "in minecraft" except for in mods and as the hacked account that started it, if you've deleted a Herobrine mod, you'll need to reinstall it. If you are genuinely talking about vanilla minecraft, then you can't add him again.
It depends which mod you are using. Every Herobrine mod will be slightly different, you'd have to check the documentation that comes with that specific mod.
No. There is no Herobrine in Minecraft.
You can't. Herobrine is NOT, nor was he EVER, in Minecraft. Any evidence you've seen of him is fake.
Herobrine was never in Minecraft.
Herobrine was never in Minecraft. It was just a joke from Notch. He never had a brother named Herobrine.
You go out at night and get killed by zomies.
Herobrine is not a part of any version of Minecraft, it is unlikely he ever will be.
There is a Minecraft player with the username Herobrine but they have not been noticeably active.
The only way to spawn herobrine in minecraft is to use mods as you cannot spawn him in vanilla minecraft.
Herobrine has never been in Minecraft, any edition.
Herobrine was never actually added to minecraft. It was just a rumor going around.
No. Herobrine is a myth. He is NOT, nor was he EVER, in Minecraft.
It depends what mod you are using, you'd have to follow the instructions outlined in whatever Herobrine mod you have.