Hi @winter_nam,
Welcome to the community forums. Of course is possible to learn Magento online.
The best way to start is to ask and try to help into the forums.
You'll find information on StackExchange too and you can start diving into the http://devdocs.magento.com/ not only for learning but to correct and improve the docs.
Another recomendation could be to be aware of Magento issues on Github: https://github.com/magento/magento2/issues (if you are technical, of course).
Also, you should read this post: https://community.magento.com/t5/Welcome-to-the-Magento-Community/Start-here-and-hello-from-me/m-p/5... (in particular the guidelines) and if you are not sure about how to use the forum you can read the FAQ: https://community.magento.com/t5/help/faqpage.
If you need information related with GDPR, you should check this: https://community.magento.com/t5/help/faqpage#gdpr
Finally, you'll need to get your hands dirty with the platform.
Cheers.
