Oh, I have that box of lace patterns, too. I'm making a scarf using the Vineyard card, 2 pattern repeats wide bordered by 5 seed stitch on boths sides.
OK, I've got the Valentine card here - very cute hearts! Are you trying to follow the words or the chart? Since you only want one heart, I think it will be easier to follow the chart on the back of the card. The single heart starts on row 19, so start there, and just follow the chart row directions inside that bold box, row 19 - 33.