You really really don't want to store anything in the concrete folder. You should create a new images folder outside the concrete folder and move everything there (and update your css and theme files to point to the new location).

As jordan said, you should never touch anything in the /concrete or /updates folders

Are you all talking about the *same* "concrete" folder? I might well refer to the directory I installed Concrete5 into as "the concrete directory." Without checking INSIDE the installation directory, one might not realize there is a folder with the name "concrete" folder. The directions are a bit terse here, for such an important bit of info.

I wonder if many upgrades have gone bad by people replacing the contents of the INSTALL directory with everything inside the folder that expanded from the downloaded zip file.

I would be nice to be able to upgrade from within the Dashboard. See for example how smoothly this works in WordPress installations.

I totally sympathize with this statement. The "concrete" folder has felt a bit ambiguous to me. Does that mean my C5 installation directory or the sub directory? However, I can't compare the overall experience of WP to C5.

Hello.
The /updates folder has several folders belonging to the several updates made now and then.
Is it not safe to delete the old updates' folders?
Thanks

I do not know for certain, because I have never tried it. But I would guess that you could remove older versions from the "updates" directory. But you should probably test it out first -- back up those older version folders first (so don't just delete them, but move them somewhere else). And of course be careful that you are not removing the current version.

Please note, however, I am just guessing here -- you need to take steps to avoid potential breakage by backing everything up first, otherwise you might wind up in trouble.