I have tried to make a cupcake bouquet and used tooth picks to secure the cupcake to the styrofoam but was not to secure the cupcakes fell off. I heard of some people using plastic cups and putting cupcake in but what do they use to stick the cup to the styrofoam?

I use the cups, and staple them together...then put them in a pretty bowl, or wicker basket, with tissue paper. Start with 3 in a circle, and just start adding them to the outside to make a round bouquet. You don't need styrofoam. They come out really pretty. You can also use decorations in between the cupcakes. Such as flowers, candles, firework looking displays for 4th of July. My friends and family love these and they are so easy!!

KHalstead gave us all the most informative tutorial on making cupcake bouquets! Here is the link:
http://cakecentral.com/cake-decorating-ftopicp-6751081-.html

I used a styrofoam ball, which i covered in royal icing (i coloured the royal icing green), then stuck the cupcakes in with toothpicks. The royal icing helped to glue the cupcakes to the ball. I didn't have any problems with the cupcakes falling off.
The picture is in my photo gallery.

what kind of frosting are you using?