I have spent the last several days learning Zen Cart and implementing/upgrading the zen cart for a client. It wasn't easy, but I'm almost complete. The hardest part was finding how to update the database "patch" as it said. I had to re-upload the zc_install folder, then run http://www.myclient.com/zen/zc_install/index.php and go step by step like it was a new install - where it then told me it needed to upgrade the database. Then, I scrolled ALL THE WAY DOWN to the bottom where it said "update the database". I followed the steps from there and it went quick and easy. It was getting there that was tough. ALWAYS remember to back up your database before any upgrade.