Because its 8-bit style every 2x2 square equals 1 pixel, so its accurate with the real thing. Its about 3-4th actual size so you can still use it, just not as an actual pickaxe.
The steps are in the photos i've highlighted the pieces you need to add.
Step 1: Parts Needed
The first photo in each step with building is what pieces you'll need for that step.
Step 2: Handel Base
Make "steps" with the 2x6 plates, placing each one 2 studs away at the top. (see photos)
Step 3: Finish The Handle.
Its the same sort of technique as the first layer but you're crossing over the first layer in the opposite direction to lock it together. (see photos.)
Step 4: Make The Head
Step 6: Head, Part Two
Step 7: Head, Part Three
Step 8: Head, Part Four
Step 9: Putting it together