I agree that putting it aside until you feel more comfortable with triangles might be the most helpful. Find a quilt pattern with a few triangles so you can get comfortable with doing them and build your skills. Some people are able to just jump in and do it and others need to take it more slowly as a step by step process.
As for signing up for any classes you need to review throughly what they are offering in any class and decide at that point if you want to do it. If it wasn't stated that this would be a hand quilting class and I didn't want to do it I would request my money back so I could join another class of my choice.