I teach windsurfing and i find my most important task for the first few lessons is to encourage people. It's so hard to do all the things at the same time right and it's easy to get discouraged falling in the water time and time again.

But it's totally fine to keep falling over and messing up. That's a normal part of learning. The trick is to see the fun in the messing up and trying. Someone screaming at you and being judgemental at such a time is the fastest way to kill your fun. I'm sorry that instructor did that to you.

I just want to encourage you to go out and play again, by yourself like you did before your lesson. See if you can find that fun. Don't let one jerk ruin it.