Hello,
Just figure out what colors of yarn you would like to use foe the heart and then make your stitches onto the plastic canvas. YouTube has some great tutorials on how to do plastic canvas if you need to see videos. I am not sure if they have any videos on stitching on the hearts but if you know how to do plastic canvas stitching, then you just apply that to the heart shape instead of a canvas sheet.
~Kristi @ EPC