I have my main character going to a far away city, but I need a reason why. I know he wants to be something great, and he is going to meet the king but doesn't plan on it.

That is a big sort of problem, because you really want your story to flow from your characters instead of having it forced upon them. I cannot really give you much specific help, not knowing your story, but I can give you some pointers.

1) Be tragic, especially at the beginning and middle of your book.

2) Don't make it too heroic (unless it turns out tragic instead). Good characters are made of a network of weaknesses.

3) Develop the plot behind that point in the story. Having the need for him to go to that point in the back of your mind will help characters pop up before that point which will lead you naturally in that direction.

I have had that problem too, and it was years before I got the answer. So be patient.

Ok thanks.

Could it have something to do with coming of age? Or is he older?
That's not exactly tragic, though.

never mind, I got it set now

That's great! What is it?

He wants to be something great, so he goes along with a someone who goes around trading stuff.

Sounds good!