The way to get the most out of a class is to listen, watch, then do whatever step the teacher is on. If you have questions, ask them. If you don't understand something, ask the teacher to explain again. And have fun. Enjoy what you are doing and don't stress. I haven't met anyone yet who has made a "perfect" quilt.
I would suggest that you stick with what's being taught in the class. Once you learn how to piece a top, adding sashing is just another step in construction. There are several different types of sashing -- plain, with cornerstones (plain or pieced blocks (4- or 9-patch or stars)). Also, see if there are going to be additional classes. Maybe one of them will include sashing.
Welcome to the wonderful world of quilting.