Besides training for Oracle University, Oracle has a couple of free learning and training resources out there on the web too.

https://livesql.oracle.com --> A SQL scratchpad that also includes scripts and tutorials.

Oracle Live Labs (https://apexapps.oracle.com/pls/apex/dbpm/r/livelabs/home) --> Granted, while it's easier googled as "Oracle Live Labs" than to remember that URL, it does, however, provide free Hands-On Labs for users.

https://oracle.github.io/learning-library/ --> The instructions for the Hands-On Labs above and more can be found in the learning-library

asktom.oracle.com --> I fully free Q&A portal where you can ask Oracle Database employees for help. Furthermore, it offers regular "Office Hours" live webinars and an entire course of learning Oracle Database: https://asktom.oracle.com/databases-for-developers.htm