Simple question about collections

Alright, so.. Let's try this:
1) I have a view which one way or another calls a controller action and
wants to update a div.
2) This controller action finds a collection of records and does a
render :partial with said collection
(e.g. : @patients with Patient.last and Patient.first)

3) ... What's the partial going to look like? This is where I don't
understand how to use collections.

If I do a ":collection => " call, what exactly am I asking Rails to do..
And then how do I help it do that?

If I do a ":collection => " call, what exactly am I asking Rails to do..

You are enabling a local variable in your partial with the same name
as the partial. The variable name will be singular and will be
initialized to each of the values that :collection contains.

Here's an example: