How do you get nether bricks in minecraft pocket edition?

You need to build the nether core. Here is what you need:

• 4 gold blocks
• 12 cobblestone blocks
• 1 nether core reactor
• A sWord to kill pigmen

The nether core is just a box of Obsidian or Netherrack were you can get the most of the items you can get like glowstone dust, gold ingot, iron ingot, and, for some reason, cactus.