##show.html.erb
<h2>Comments</h2>
     <% unless @post.comments.blank? %>
        <div id="comments">
                <%= render :partial => 'comments/comment', :collection => @post.comments %>
        </div>
    <% else %>
                <p>No one has commented yet.</p>
    <% end %>

##_comment.html.erb

<div id="<%= comment.id %>">
                        <div id="comment_username">
                                <%=h comment.user.login %>
                        </div>
                        <div id="comment_body">
                                <%=h comment.body %>
                        </div>
                        <div id="comment_toolbar">
                                <%= render :partial => 'comments/reply_link', :locals => {:comment => @comment} %>
                        </div>
                </div>