I know now you want to learn your favorite song. What I do is just google "song title chords" and the first link is probably going to be ultimatguitar.com I do enjoy this website! If the chords are too complicated all you do is click on the ver # and find another version with simpler chords and good reviews.
When you find a good song with simple chords and good ratings play the chords while singing the song. No matter if your a horrible singer this is the best way to learn. I would start by playing only down stokes. Once you have master chord transitions, now you can play the strumming pattern where I also find online or just play around to see what sounds best.
I really hope this helped! If you have any questions, go right ahead and I will answer them :)