Concentrate on your text, make sure that you know your stuff before you get up there, then you'll have nothing to worry about.
And just remember, no one knows what is a mistake in your presentation and what is not unless you point it out to them. Don't point out to them that you're nervous or unsure. In my acting classes, we were told that you can always fool people by pretending to know exactly what you're doing. I guess that pretty much sums up acting!
Have confidence in yourself, present to the last person in the farthest row, and think how great it will be when it's over and no one is paying attention to you again! (And it may help to think that your dick is getting bigger all the time.)
Good luck.