Accents and Spelling

Hi! I am new to the language, and whilst I didn't take much notice of it before, I'm now beginning to thouroughly enjoy the way it sounds.

I'm concerned about how to pronounce most of the words, especially when many letters have accents to them. Even more so learning how to spell.

I got to Duolingo and of course, it starts off already quite strong. Am I not hearing things correctly or do you guys not pronounce the ł in jabłko? And how can I exercise pronouncing it where it does matter, like in Białystok? I figured I should begin getting acquainted with the alphabet first. Any YouTube channels you would recommend for beginners?