I understand that fear, but the best thing you can do for yourself is face it. You will make mistakes, but you probably won't get yelled at for it. It's not professional or proper in the workplace. And seriously? What's the worst that could happen? Getting yelled at is no fun, but it doesn't hurt you. You will survive.

Unless you are afraid of something more than "being yelled at"? Maybe afraid of being hurt physically? Or afraid that a failure makes you a failure? Or of losing your job after one mistake?

Once you name the fears and see how unlikely and ridiculous they really are, you have a better chance of overcoming them. Will it be easy? Nope. Not in the least. But is it possible? Yes.