Download a singleplayer command for the version of minecraft you currently have.
AND A CHART OF ALL MINECRAFT ID's OF CUBES
THIS IS THE SINGLEPLAYER VERSION!
Make sure you go on minecraft forums "I cannot post outside link"

When inGame Enter "/item [id] [ammount]

MULTIPLAYER VERSION:

When inGame Enter "/item [id] [ammount]

Depends on server...

I can post a video later on a tut