Herobrine.
Whichever Herobrine mod you are using will say how to make Herobrine appear and what you can do what he does, each mod will be different.
Maybe if you know how to do it
It depends which mod you are using. Many mods add Herobrine, they all have different ways of summoning him or making him appear.
No, you shouldn't need to do that. Whatever Herobrine mod you use, should let him appear naturally, a texture pack won't change that.
Herobrine is just a myth created by a gamer trying to freak people out. There is a player named Herobrine, and he has the Herobrine skin, but he doesn't actually appear in single player worlds, no matter if it's Pocket Edition or Desktop Edition. There is no such thing as a Herobrine mob that appears in game. Just a person with a cool idea for a skin, and a pretty awesome name.
You'd need to be playing the PC version and install a Herobrine mod. The conditions to make him appear would be outlined in that particular mod, they'd all be different.
he is meditating
Yes and no. He was originally something from a story, that is easily made real and modded into the game. He can't appear in an unmodded game.
No. There is no Herobrine in Minecraft.
You can't, he never existed in-game. When you see the update list when you start up Minecraft, pretty much every update says at the bottom "-Removed Herobrine.", but it's a joke update, referring to the 'urban legend' of Herobrine.
Herobrine is a misnomer because the first 2 syllables is "hero" and Herobrine is'nt a hero, he's actually a villain. Brine is the short form Herobrine.