Ah yes.. Going through the same thing with Candy- new horse who is a green jumper (at least with scary things). You can go to a craft store and get plastic flowers, stick them in styrofoam and have a little flower box. Attach streamers (anything works, thick ribbon, twine, paper taped on jumps, etc.) and jump it, although do it inside or on a non windy day first! Other than repainting jumps scary colors and different types of jumps (small coop like jumps, like this but miny, small enough to walk over at first http://www.rideirishhorses.com/RockyJumpCoop260.jpg
) that's about all I can think of right now other than what people said. OH, most terrifying thing, plastic animals. Dogs, foxes, cats, etc. are awfully terrifying to horses, just place them by jumps. You could probably go out and buy a couple big stuffed animals cheap somewhere and place them by/underneath a jump if you can't find plastic ones..