Order a collection as DESC
Solution 1:
Like described on http://guides.rubyonrails.org/active_record_querying.html
@events.order(event_at: :desc)
Solution 2:
Even better, you can set a scope to sort your event and use it in your render.
In your Event model:
scope :desc, order("events.event_at DESC")
If you use Rails3, in your view you can simply do:
<%= render @events.desc %>