I had to go threw this to so I think I can explain it alittle better.
1.North island on the right(closer to olivine)
2.Go straight untill you hit the wall and go right, you sould have jumped over two little hills and then go straight up
3.Ok your on a little peice of elivated ground and you what to stay on that peice. the lader should be on the other side of the elivated ground
4.go down,right,then down again and there sould be a guy standing there
5.Talk to that guy he will let you in if you have the silver wing
6.go ALL the way to the bottom and go threw the cave that is all be it self on like a miny island(but its conected to the path)
7.And there you have it you have goten to lugia