you cant
In pocket edition you'll need iron, gold or a diamond pickaxe.
Same place as the computers vanilla Minecraft.
The same way you get iron on Minecraft PC/Desktop Edition and Xbox Edition. Just try to find a cave.
an iron pickaxe will do.
You need to craft it out of Iron Ingot and Sticks.
In order to to get iron ingots, you need to smelt iron ore.
put iron ore in the furnace (be sure there is coal in there too)
I don't know if this is accurate, but I found some under a river.
using 3 diamonds and 6 iron ingots
Try wooden tools if haven't tried those! If that doesn't help I don't know what to tell you bro!
You have to use at least an iron pickaxe or better.
Redstone can be mined underground or found in caves. You need an iron pickaxe to mine it. It is not in the pocket edition.