How do you put a ladder on a furnace in minecraft pocket edition?

Grab the material that you want to create the stair(s) with (Cobblestone, wood planks, marble (1.5), nether brick, brick) and go into a crafting bench and it should look like this.

X= Material

[ ]=Blank

[ ][ ][ ][X]

[ ][ ][X][X]

[ ][X][X][X]

[X][X][X][X]