Events in view question

I have taken an example wherein, using Ajax, the values of a second
combobox are populated by a change in the primary combobox. The code
is shown below.

I realise it will seem as though I am asking someone to write the code
for me, BUT, can someone please show me, by way of an example how to
amend my index.rhtml below to use, say a radio button group instead of
a combobox, wherein when you change the radio button group, the
secondary combobox is changed, without having to incorporate a submit
button?

I somehow need someone to kickstart me here with this, and I can
bootstrap the rest of what I am trying to do. Thanks. R. Vince

#in mycontroller:

  def create_select
    indArr=["Nordic Skiing", "Inline Skating","Tennis",
      "Triathlon","Road Racing","Figure Skating",
      "Weight Lifting","Speed Skating","Snowboarding"];
    teamArr=["Soccer","Basketball","Football","Hockey",
      "Baseball","Lacrosse"];
    str="";
    if params[:categories].index('Team') != nil
      render :partial => "options", :locals => { :sports =>
teamArr,:sptype => "team"}
    elsif params[:categories].index('Individual') != nil
      render :partial => "options", :locals => { :sports =>
indArr, :sptype => "individual" }
    else
      str="<select id='individual' name='individual'>
           <option>unknown</option></select>";
      render :text => str;
    end
end

#index.rhtml:

   <%= form_remote_tag(:update => "sel_con",:url => {
      :action => :create_select },
      :position => "top",:success => "$('sel_con').innerHTML=''" ) %>
    <p>
      Please select a sports category:
    </p>
    <p>
      <%= select_tag "categories",
      "<option>Team</option><option>Individual</option>" %>
    </p>
    <div id="sel_con"></div>
    <p>
      <%= submit_tag "Show Sports" %>
    </p>
    <%= end_form_tag %>

#_options.rhtml:

   <select id="<%= sptype %>" name="<%= sptype %>">
   <% sports.each do |sport| %>
   <option><%= sport %></option>
   <% end %>
   </select>