Apply css on form collection

I'd like to apply this style :

       .tag-wrapper
          %ul
            %li.tag.fa.fa-plus
              = tag.name

on my current code :

= f.input :all_tags, :as => :check_boxes, :collection => @tags.map{|tag| tag.name}

But I don't know how to manage collection. And for know it looks like that :

They are all display one over the over and not like a list or any other way which allow the user to click on each item.