How to summon Herobrine is quite simple but it may not work. You will need 1 mossy cobblestone, 2 nether rack, 8 gold blocks,1 flint and steal, and 4 red stone torches. First place the mossy cobblestone on a flat surface, next place the gold blocks all around it, after that place a nether rack block on top of the cobblestone then place the other one on top of the one you just placed. Next place the four torches on the 4 gold blocks that are touching the mossy cobblestone. Finally take the flint and steal and light the top nether rack on fire to summon him.