This is a duplicate question: Commenting/Uncommenting a block of Python code in TextWrangler
However, I recommend you not bother with those 9 steps and instead just download sublime text 2.
It is an excellent editor for Python (I believe that's the language its written in, in fact.) and you can accomplish what you're looking for by simply highlighting the code block and using the comment/uncomment keyboard shortcut: Ctrl+Shift+/