How Should I Handle My Stage Fright?

I'm what you could consider a "rookie" cos-player. At a convention my friends and I will be attending, we're going to do a walk-on with some costumes I've made myself. I've watched videos on Youtube of walk-ons and such. But I get terribly nervous even watching the videos themselves. I can't seem to build up the confidence to actually sit there and watch the videos, how should I handle this?