You will soon learn by doing it for the next time. BTC isn't for an average Joe so start with, no anymore with this ATH prices.
Next time when use recommended fee before sending BTC to anyone. Maybe this site will help you further on
https://bitcoinfees.21.co/ok but this site doesn't help me a lot (kinda hard to understand). so i get that the optional fee was too low and that's a reason why the transaction doesn't get confirmed? So what can i do about it now? thanks again for your help
You can use Transaction Accelerator, available here
https://www.viabtc.com/tools/txaccelerator/. Read about that more here
https://bitcointalk.org/index.php?topic=1816647.60. Although haven't really tried it yet. Good luck.
This site
https://bitcoinfees.21.co/ explains what is the recommended fee for an average transaction. As it says right now:
The fastest and cheapest transaction fee is currently 390 satoshis/byte
You used 50 sat/B and with that fee your transaction will get confirm in infinite time.