You will need 2 colors

White and an alternate color of your choice...
To make a 6" square chain 23 in worsted weight yarn
Sc in 2nd ch from hook and across, ch 1, turn (22 sts)
Sc in each st across. ch 1 turn
Repeat 2nd row for a total of 17 rows.

Now do 2 rows of sc around the square in black or alternate color. 

Using alternate color, cross stitch the hearts into the center of the squares.

You can also do these squares in afghan stitch adding the heart as you go.  (as in the photo)