Rails Recipes #31 Authenticating Users

I have figured out everything except for how to add a new user to the
database. The book gives an example of adding a user through the
command line, and that works fine. I can login using a user created
that way. I cannot, however, figure out how to add a new user from a
form. The problem seems to occur when trying to except a user submitted
password (of which there is no corresponding DB listing) and generating
a salt and hash to be stored in the DB. The method in the user model:

def password=(pass)
    salt = [Array.new(6){rand(256).chr}.join].pack("m").chomp
    self.password_salt, self.password_hash = salt,
Digest::SHA256.hexdigest(pass + salt)
  end

how do I accept a password from a view from a form, generate the
password and salt and save it to the DB. Here is what I have for the
view form

View:

<%= form_tag({:action => 'new_user'}, :multipart => true) %>

<div class="new_i">
                  <p><b>Username:</b><br>
                    <%= text_field("user", "username", "size" => 20 ) %>
</p>
</div>

<div class="new_i">
                  <p><b>Password:</b><br>
                    <%= text_field_tag("password",nil, "size" => 20 ) %>
</p>
</div>

<%= submit_tag(" Register ")%>
<%= end_form_tag %>

I changed the text_field to text_field_tag because the fact that
password is not a line in the DB was raising an error. I can't figure
out how to handle this in the controller in :action => "new_user"