XF 2.1 What files and folders should I change permissions for?

[dadpuberty]

XenForo 2.1.0 is now available through upgrade check.
I clicked Upgrade now to attempt a 2.1 click update.

However, I saw the following message.
"The following issues have been identified when a one-click upgrade is possible: The files are not writable."

What files and folders should I change permissions for?

 

[dadpuberty]

I was able to check the path through the control panel error.