Begin rolling by turning over 1/8" on edge
After a few rolls, begin to make a couple of small (1/4") tucks so that the "petals" begin to flare out a bit.
Pin the rose center to your 3" square of tulle (pin from underneath)
Gather the rest of the ribbon gripping the tail end of the lower wire and by gently sliding the ribbon along it. Scoot the gathers carefully along the wire so you don't break the wire, until you have gathered the entire length of the ribbon (only on the lower edge - the upper edge is left full.)
Continue to wrap the ribbon around the center, pinning as needed to the tulle/buckram from underneath.
When you get to the end, tuck the unfinished end in under the "rose" so it won't show or unravel.
Sew the rose to the tulle from the back, tacking it down as needed (you don't need to stitch the entire length of the ribbon, just make sure it won't come unrolled anywhere.)
In the first picture, I used the last 4 or 5 inches of ribbon to end in a bud to the side of the rose. Leaf tutorial found here.