Turtle programming using blocks in the minecraft world

Yesterday i saw this Thread Ultimate Turtle and i really liked the idea so I wrote a programm that lets a turtle have actions depending on the blocks it encounters.

Cobble makes the turtle turn left.
Planks make the turtle turn right.
Logs means there is a tree to chop down.
Wool selects and inventory slot (by color)
Workbenches call turtle.craft
Sandstone puts items of the same kind in the chest.

and many more…

Spoiler

This picture shows my tree farm (right) with a auto charcoal smelter (middle), a torch crafter (left) and a bit of sorted storage (bottom).

pastebin get p7UFC50k blockTurtle

cool

thats a nice Program there, but can you explain how to use it correctly?
I don't really understand the system of this program.

Do I need to put down the blocks? if yes, can you give me a list with all the different blocks the turtle can detect and which functions they have?
if no, does the turtle need to have something in his inventory to build a system like this?

On each movement, the turtle checks for blocks above / below / in front of it. If it finds a match for any of the blocks listed in the "actions" table then it performs the code associated with that block within that table.

So yes, you put down the blocks, and the turtle uses those to determine your instructions to it.