I am happy to be here but how can I find able person that will guide me through my stay here.
This is a bad approach. If you look for a person to help you, you can easily stumble on persons that want to scam you or who may (willingly or unwillingly) mislead you.
Since you are an upcoming backend developer you may assimilate more info from pages like
https://learnmeabitcoin.com/ or
https://electrum.readthedocs.io/ than from watching YouTube movies.
How do I commence my learning in the most subtle way?
Is there addictional materials available? Like link, videos, PDF
The best is imho to read a little from reputable sources.
I'd start with bitcoin whitepaper:
https://bitcoin.org/en/bitcoin-paper (if you're from UK, just ask for a different source)
Then I'd go to through Mastering Bitcoin, which is free here:
https://github.com/bitcoinbook/bitcoinbookAfterwards, the links I've started with can be of help too.
When you have some reading done, you can start asking. People here will be more than happy to help you, as long as you don't ask things already asked 100s of times.
The search feature of the forum can be of help too, or maybe
https://ninjastic.space/search would make it even easier.
Make sure you make your topics when asking questions instead of hijacking others' topics.
Enjoy the ride!