You will need to mine and smelt 24 Iron Ingots to produce the Iron Suit.
To get this you will need to mine Iron ore in the ground, crafting table, and a oven to smelt the Iron ore into ingots.
Once you have enough Ingots of Iron you will need to make one of each of the Items below
Helmet - 5 Iron Ingots
Body - 8 Iron Ingots
Legs - 7 Iron Ingots
Boots - 4 Iron Ingots
*Note there is no tutorial level on the Pocket Edition at this time.