If I look at the README, you should have a partial like this one:
<%= fb_connect_async_js %>
<% if current_facebook_user %>
<%= "Welcome #{current_facebook_user.first_name} #{current_facebook_user.last_name}!" %>
or
<%= "Hello #{fb_name(current_facebook_user, :useyou => false)}!" # link to facebook profile %>
<%= fb_logout_link("Logout of fb", request.url) %><br />
<% else
# you must explicitly request permissions for facebook user fields.
# here we instruct facebook to ask the user for permission for our website
# to access the user's facebook email and birthday
%>
<%= fb_login(:text => 'Log in', :perms => 'email,user_birthday') %>
<% end %>
In that case, you just have to pass the options to fb_connect_async_js
:
<%= fb_connect_async_js :channel_url => 'http://blahblah' %>
... rest of the partial ...
If your partial doesn't look like the one above, you should edit your question to post yours (the full one).