Here is a practice track to help you get familiar with playing 3 beats to the bar. While a great deal of music commonly heard in rock and pop is in 4 beats to the bar, playing in 3 beats to the bar is important for the well rounded musician, even if it’s only so you can play the bridal waltz if you get wedding gigs!
The chord progression is
||: Am |Am |G |Am : ||
It is a slow (90 bpm) 3 beats to the bar, with each beat divided into shuffle eights, which you can hear if you listen to the drums.
Use the notes of the A natural minor scale (same as C major) to construct a melody over the progression.
Practice Track: A natural minor, 3/4 time
Enjoy!