My name is Jens Bergensten, but I'm better
known as Jeb. I'm the lead developer on Minecraft

here at mojang.com. I think I was 11 or maybe
12 and I started programming because I wanted

to make games. One of my father's friends
told me that in order to make games you need

to learn how to program. So that's how I got
started. I like designing and figuring out

the architecture of things. That's what I
really like about Minecraft. Over the next

hour you're going to learn the basics of computer
science by programming Alex or Steve to move

through a simulated piece of a Minecraft world.
Traditional programming is usually in text,

but today we'll use blockly: a system which
uses blocks that you can drag and drop to

write programs. Under the hood, you're creating
JavaScript code. The concepts that you'll

be learning are what computer programmers
use everyday and are the foundation to computer

science. Here at Mojang we use these same
concepts to make Minecraft work. Before you

start, you'll pick your character. I'm going
to choose Alex. Let's build code for a program

that will help her move around the screen.
Your screen is split into three main parts.

On the left is the Minecraft play space, where
your program will run. The instructions for

each level are written below. This middle
area is the toolbox and each of these blocks

is a command that directs Alex's actions.
The white space on the right is called the

work space and this is where we'll build our
program. If we drag the moveForward(); block

to our workspace and then click Run, what
happens? Alex moves forward one space on the

grid. And what if we wanted to do something
after she moves forward one space? We can

add another block to our program. I'm going
to choose the turnRight(); block, and I'll drag

it underneath my moveForward(); block until
this orange line appears. Then, I'll drop

it and the two blocks will snap together.
When we press Run again, Alex will perform

the commands that are stacked from top to
bottom in our workspace. And if you ever want

to delete a block, just drag it from the stack
back to the toolbox. To undo your changes

and to get back to how the level started,
use the Start Over button in the top right

corner of the workspace. One more thing, you
see the little triangle on the turn blocks?

Anytime you see these triangles, it means
that you can pick a different option. Let's

start coding!