Trying to play a song by ear? Tips?

I am trying to play Kadawatha's Agape on the piano. I am good with
getting the higher notes/melody (I'm not exactly sure what it's called
:D) right, but the chords give me trouble. All I can do for the fifth
chords is either play the notes individually or all together. It is
very boring.

Any tips on things I can do to "spice" it up? XD

No of any videos on YouTube that might help?

Any help is appreciated. Thanks!!! :D