Learn to play the melody of this song with your right hand alone.
Use correct fingering (the numbers between the treble and bass staves) and you will have a smooth melody.
Read the letters above the treble staff to play automatic chords to harmonize the melody.
The rhythm you add will be a waltz since the song is in 3/4 time. Play the two G's at the beginning of the song on the count of 3, then begin the chord on the count of 1 in the next measure.
Begin ver-r-ry slowly with a metronome speed of 60.
When you can play it well at that speed, then try it faster.