I was inspired by an instructable and made my own version.
Great flexibility with where you want to put the ribbon (back/front/on the sleeve). When you get tired of this you can just take it out and you have your top back the way it was.
Take the t-shirt/shirt/top you want to decorate and fold it inside out.
Put in the safety pins about 2 finger lengths apart as you go down. and as you go down place the safety pin about 1-2 cm towards the center than the previous pin.
TIP:(easier to do this after you have added the ribbon-) you could put tape/fabric tape over safety pins to stop the fabric from pulling/stretching as well as holding pins -so they don't prick/come undone if you are an active person.
Turn the top inside out again so it is the right way.
Thread the ribbon through the pins and voila!