its all about knowing where to look and how to use search engines.
if i see a video of or hear a song i like, i will listen to it a bit and get to know the song, learning the lyrics, and getting the rhythm down in my head. from that point, google is your friend. search for the lyrics of the song. and make sure the lyrics you have are right. then search for the chords to the song. a good site for that is ultimate-guitar dot com. for jawaiian style music, tropicalstormhawaii dot com is a great reference. thats how i find out what chords to use. from there, i start making my own corrections and making up rhythms and accents to suit my own needs and abilities.
dont get stuck on only one resource. there are many all over the internet. use them for as long as you need them. eventually, you will start to notice that you will need them less and less.
and after enough time (varies from person to person) you may get as good as my brother bugoy and hear a song... disappear for 30 minutes... and come back playing the song from start to finish like he wrote it himself. hahaha, i hate him for that.