Basically you determine how long you want the ribbon necklace to be, and add about 3/4 to 1" to each end (or 2" to the desired finished length). At each end, fold the ribbon over at the 1" location.
On one end, slide on a clasp with an attached jump ring and use either 20- or 18-gauge half hard half round wire to wrap the end into the main length. Repeat the same procedure on the other end, after sliding on a jump ring with an attached chain with a small headpin charm end for the final touch!