I'm trying to learn Magento theme structure, I've been told that I should create a package and a theme folders under app/design/frontend and also under the skin directory, but whenever I save the configuration , I get package with this name does not exist and cannot be set.
What you've done is definitely the right thing to do.
To me, it sounds like a permission issue.
Check the permissions on the
base/default folder in both
skin and apply the same permissions recursively on your
tutsplus folder, that should fix your issue.