If you have not followed the instructions in the "Preparation" topic, do so before proceeding.
By now, you should have downloaded 1 or more upgrade files. You will need to repeat the import process for each file, starting from the oldest to the newest. This process is explained in detail in the topic "Backups : Restoring a Database Backup". If you receive an error at any time during the upgrade process, you will need to stop, document the error, and submit a support request:
Proceeding to apply subsuquent upgrade files after receiving an error will definitely cause problems with your installation.