Minecraft Pi had some built-in constants (variables that can't change) for blocks but we need to import them so press Enter on the third line and add the following on the code:
from mcpi import block
Now, we can call a block using the constant instead of a number. The constant is longer but a bit easier to remember. For instance, stone is block.STONE.id. You can substitute the name of any block type in ALL CAPS with _ for spaces. There is a list of the names of all of the block types on this page a little ways down.
Remembering numbers or typing out block IDs can be frustrating. Can you create a variable that stands in for either the number or block ID? Once you think you have it, make a blank line after our import and add your variable. Try using the variable as an argument instead of the number or block ID to see if you created it correctly.