Now that your case is full of knitting needles, just roll it up so that the end with the ribbon is on the outside. Wrap the ribbon around the bundle once or twice, then tie it closed.
As you can see, my tail end ended up a little long using a whole yard of ribbon, so feel free to use less or trim away the excess on your project. Ribbon usage may vary depending on how many needles you have in your case (mine was not completely full, thus not very thick).
