http://pastebin.com/K4wRuK44 this is the code
and this is the error
this is the line with error
leftWall.center = new Vector2(mainCam.ScreenToWorldPoint (new Vector3 (0f, 0f, 0f)).x – 0.5f);
Welcome to the wonderful world of debugging!
I suggest you revisit the tutorial and figure this one out solo.
You’re only going to learn through trial and error, so others doing it for you is counterproductive. 🙂
Give it another couple of goes, it’s undoubably the simplest thing.
Use the error as a clue as to what you need to check.