I used 12" by 12" cardstock paper, cut into 3/4" strips
Fold each strip in half
Then fold the two ends in towards the middle and either staple or glue them together.
For the next heart make sure one side of the strip is on the outside of the first heart and the other end of the strip goes through the heart. Then staple the ends together as before.
Continue until the garland reaches your desired length. I copied the original poster and I am using it as a chandelier decoration.
The original post also used two pieces of paper so the outside of each heart was a different color/ design. Just make sure the outside strip is longer than the inside one.