You can't move blocks. See the world as a giant 3d grid (or table) and you can simply fill in the cells with a material (dirt, stone, glass, etc.). Cells always stay in the same position, so you can't move them.
If you want to give the impression of a moving block, you need to set the material of a cell to the material you want the block to be, and every time the block 'moves' you need to reset the old cell back to the old material (air maybe?) and fill the new cell with the block material.
Code:
World = cRoot:Get():GetWorld()
World:SetBlock( X, Y, Z, E_BLOCK_SPONGE, 0 )
This sets a block on coordinates [X, Y, Z] to a sponge material