User Guide
On your FTP server, inside the "prestashop" folder, you should delete:
The {{/install} folder (this subfolder contains the update tools).
The README files (contain information about the PrestaShop install).
The CHANGELOG file (contains information about the latest changes in
PrestaShop).
You can now access your store's front-office at
http://www.myprestashop.com/prestashop (change the URL accordingly).
Did you follow these 3 steps?