There's basically two ways to go with this particular project: hand roll all of your own paper roses, like the ones seen here, or buy ready-made flowers.
Andrea Atwater twirled all of these roses herself, varying the size and tightness of the roses to give the tree an interesting, dimensional look. Choose a red paper that isn't too thick to roll, but not so thin that it won't hold its shape. Construction-type paper would work, but a cardstock would be too thick. Here is an instructional video from Crafts and More with Misil
If you'd like to purchase pre-made roses, here are three from our store to choose from:
Once you've decided on your roses, simply glue them onto a cone form, like the one below, using hot glue and voila! Beautiful holiday centerpiece.