Question (Possible Spoilers?)

[Ragnarok]

Ok so I'm trying to advance on the Monster Arena and I'm to the part where I have just beat Seymour on the mountain path, and it says that I need to go back to Besaid. So my question is, how do I get there, I tried going all the way back and it wont let me leave the Thunder Plains because it says that sombody is after me or something. So how do I get there? Thanks.

[boys from the dwarf]

continue to zanarkand and progress the story until you get an airship.

[Ragnarok]

Ok that answers my question, thank you.