The best place to start is always the official source. LEGO's Service site maintains building instructions for thousands of sets, including the NXT 2.0.
By pairing your legacy LEGO Mindstorms NXT 2.0 hardware with downloadable PDF manuals and modern software patches, this timeless educational platform can continue to teach robust robotics skills for years to come. lego mindstorms nxt 2.0 building instructions pdf