Dip the rice paper in warm water. Don't soak it for too long - it will soften too much and will be impossible to roll up. Transfer to a damp cutting board and starting at the bottom third of the wrapper, add spinach first and then layer chicken, bell peppers, cucumbers, and cilantro. Do not overstuff your roll. Gently fold over once, tuck in edges, and continue rolling until it looks like a burrito. Serve with peanut dressing.