Newbie question: page navigation

Absolute beginner here - sorry if this the answer is obvious - but i don't know enough to search effectively ! I've started from generated scaffolding. There are now two routes to a page that adds a 'contact' . When a contact is successfully added I would like the system to return to the page that called it . When I go into the add contact page I'm passing a parameter to indicate where its come from : <%=button_to 'New Contact ', :controller => "contacts" ,:action => 'new' ,:from_folder=>'1'%> gives a url of http://localhost:3000/contacts/new?from_folder=1

I've changed the contacts controller create method as follows   def create     @contact = Contact.new(params[:contact])      @temp = params[:from_folder]    # @temp = 1     if @contact.save       flash[:notice] = 'Contact was successfully created.'       if @temp == '1'         redirect_to :controller => 'folders' ,:action => 'new'        else         redirect_to :controller => 'chs' ,:action => 'index'       end     else       render :action => 'new'     end   end

BUT this doesnt pick up the params[:from_folder] . Firstly is this a sensible way to approach this ? or is there another way ? secondly - why isnt the controller seeing the parameter ? The new contact form is still using

<%= start_form_tag :action => 'create' %>   <%= render :partial => 'form' %>   <%= submit_tag "Create" %>

Thanks in advance

Kath