Read the description and then continue from here

20th : Sniper Island

21st : Giant Terror

22nd : Return to Swamp

23rd : Weatheria

24th : Snow Island

25th : Solar Kite

26th : Gaso

27th : Vivalada

28th : Whale Fins

29th : Kuja Kingdom

30th : Bio Hill

31st : Death Bridge

32nd : Side - Affects

33rd : Hollow Castle

34th : Arabia

35th : Haunted Mount

{ Endwar Saga }

36th : Mary Geoise

37th : New Marineford

38th : Finale