When I first added the heart, it was too big and the center was empty allowing the background paper to show through.
I first resized the heart but did not like the dot in the center.
To hide the dot, I added a circle punch and resized it to fit over the heart.
Using the Color Fill button, I chose the same color as the background paper
then the Arrange -Order-Send Backward function.
This moved the plain colored circle behind the open heart and hid the dotted background paper.
Alternatively, if I had wanted the heart to be a contrasting color, I could have chosen another color to fill the punch with