Hi Fernando

Odoo is evolving very fast with a new version every year, even if you concentrate only on the new version, there will always be a lot to learn and evolve.

You can simply create a demo-DB at: https://www.odoo.com/trial, choosing the desired Apps and selecting "try it free".
Two more tips:
- Buy or "print yourself (download) scale up: https://www.odoo.com/page/scale-up-business-game
- When creating your free DB, add "edu-" before the company name and your DB will be available for testing for 10 months.

Have fun

BR

Ricardo Gross