app/views/profile_themes/add_image.html.erb
<%= form_tag({:action => 'add_image', :id => @theme.id}, :multipart => true) do %>
<%= labelled_form_field(_('Choose the image file'), file_field_tag(:image)) %>
<%= button_bar do %>
<%= submit_button(:add, _('Add image')) %>
<% end %>
<% end %>