when using a text editor you have to tell your rails app that the area is html safe. This is (by default) not the case as people could attack your site by using a text box you have put into your app.
by declaring an area as html safe you should be able to use the html tags as you like. be aware of the security risk for using this.
e.g.
<div class="description">
<%= @foo.foo_desc.html_safe%>
</div>
Hope this clears it up for you.