Take your zipper and cut off some fabric on the sides, so only less than a centimeter remains.

Zip it up to about 1/4 of the length

Cut off the excess fabric off the end of the right side

Fold the left half exactly as shown in the picture

Fold the right half on top of the left and line it up

Sew in place

Unfold it, and it should look like this

Cut off the excess fabric on the left half

Fold it again and sew the front half to the back

Flip it over and trim off the excess fabric

Take your two jump rings and twist them open with your fingers. Set them aside. Take your needle and poke two holes in the top corners of your zipper heart. Make sure you poke the holes next to the metal part of the zipper. You might want to get a thicker needle to make the holes big enough

Take your jump rings and pull them through the holes you made, but don't close them yet

Take your necklace chain and fold it in half to find the middle

Use your scissors to cut it in half

Take then end links and pull them through the open jump rings. Close the jump rings.

And voila! You have finished your zipper heart necklace!