Don't redo the work, just keep going. It's entirely normal for students to have lots of issues with their texture work, as its role in Lesson 2 is more to introduce the problem (especially introducing it as a spatial reasoning problem where we think about the relationships between the forms casting the shadows and the surfaces receiving them, when designing the shadow shapes themselves), so that when we start delving more directly into spatial reasoning through the constructional drawing exercises in Lessons 3-7, it can help point what students learn in the intended direction.

All in all, don't worry too much about it, and at the end of the day, always remember that the purpose of the homework is to create a body of work that represents what you do understand, what you don't understand, and how you're currently going about approaching the work. If part of that involves missing instructions, then it's worth having that called out by someone else, because it'll have far more impact than if you simply catch yourself and fix it quietly without ever having anyone else notice.