Rails Kaminari - How to order/paginate arrays?

I'm following the railscast for Kaminari (http://railscasts.com/episodes/254-pagination-with-kaminari). But I'm stuck with the controller part.

In my controller, I have something like this:

def index
  @articles = (params[:mine] == "true") ? current_user.articles : Article.search(params[:search])

  respond_to do |format|
    format.html
    format.json { render json: @articles }
  end
end

And now I'm not sure how to chain the methods, order, page and per, like in the screencast .order("name").page(params[:page]).per(5). I keep on getting the no method 'order' in Array. I know I can't call the methods on arrays but how else can I chain them?