Rails: How do I use hidden_field in a form_for?

I've read this, but I'm new to RoR so I'm having a little trouble understanding it. I'm using a form to create a new request record, and all of the variables that I need to send exist already. Here is the data I need to send (this is in a do loop):

:user_id => w[:requesteeID]
:requesteeName => current_user.name
:requesteeEmail => current_user.email
:info => e

Here's my form, which works so far, but only send NULL values for everything:

<% form_for(:request, :url => requests_path) do |f| %>
    <div class="actions">
        <%= f.submit e %>
    </div>
<% end %>

How do I use hidden_fields to send the data I already have? Thanks for reading.

Ref hidden_field or hidden_field_tag

<% form_for(:request, :url => requests_path) do |f| %>
    <div class="actions">
        <%= f.hidden_field :some_column %>
        <%= hidden_field_tag 'selected', 'none'  %>
        <%= f.submit e %>
    </div>
<% end %>

then in controller

 params[:selected]="none"
 params[:request][:some_column] = request.some_column

Note when you used

   <%= f.hidden_field :some_column %>

it change to html

<input type="hidden" id="request_some_column" name="request[some_column]" value="#{@request.some_column}" />

and when you used

<%= hidden_field_tag 'selected', 'none'  %>

it change to html

   <input id="selected" name="selected" type="hidden" value="none"/>

You can send a custom value as a hidden input for your model like that:

<%= f.hidden_field :your_model_field_name, value: 12 %>

Where value: 12 is just a demo, but you can pass whatever value you need.