How do you get to fullmoon island Pokemon Platinum?

What you do you go to canaval city first. Then near where the sailor is by the docks there is a house saying it is a sailors house. you should see a boy in bed with a mother with him. talk to them both then, go talk to the sailor outside and he will offer to go to fullmoon island you say yes and you'll go. you arive and go into an entrance like you see in eterna forest. you will see cresselia. you talk to it. it will fly off but it drops a luner wing. you pick it up nd go back to the sailor and go back to canavale city and talk to the sick boy. it will say that you're lunar wing will glow and the boy will wake up. then the sailor goes in and talks to you. then you talk to the sailor and he will offer to take you to iron island and fullmoon island anytime!! dont worry, you can catch cresselia again like mespirt.