Pathfinder spell attack/damage - How does this work??

I am trying to switch my attacks to run from the sheet, rather than the bazillion macros I currently have set up. I'm having difficulty with the box for damage - I have tried putting in both 12d6 and [[12d6]], but both of them just show up in the chat as "12d6" instead of rolling the damage. Am I doing this wrong? The spell is intensified fireball, so it's just a flat # of d6 per level.

From within the spell's repeating spell entry, use the Attack and Damage sub-section to enter damage. You "can" use the create attack if you want to see your Fireball with your attacks, but not necessary.