So a typical layout looks like:
I recommend PHP for a really simple thing (like email-form, shoutbox, etc), because it is easier to set up. The amount time you save by coding it in Rails will be nullified by the amount of time you spend extra setting things up. Rails is better for medium/large things. A good thing to ask yourself is: "is this site an application?" if it is, chances are good Rails is the way to go.
<%= stylesheet_link_tag 'style' %> <!-- You can use inline Ruby here. This creates a <link ... /> tag -->
<%= yield %> <!-- yield will be replaced by a page specific template -->