If you have an old Prestashop version running in your hosting, then you should consider upgrading to latest stable version of Prestashop. (currently is 1.3.1). This is a step by step guide for upgrading process :
1) Backup your current files and database. I rather to create a folder called BACKUP, and copy all files into that folder. For the database, export in phpmyadmin (be sure that exported database is working and not corrupted).