No, thanks you Jeremiah for such a blazing fast answer.
Now, this is embarrassing, I forgot the address! http://www.ateliechrislima.com.br
So, after I posted this I installed another WooCommerce plugin (I had only WooCommerce and your plugin before; except, of course, for the "stock" plugins) and I noticed the shopping cart showed up on the menu.
I was about to come back here and update the topic as resolved, but before that I tried to make a tiny adjustment to the plugin, changing the code in order to adapt it to Brazilian Portuguese. I made changes to lines 131 and 132, as pasted below. The shopping cart menu did not, however, update to my changes: it still shows "1 item", "2 items" and "View your shopping cart".
So, I'm confused. Maybe I did do something wrong in the first place?
$viewing_cart = __('Ver seu carrinho', 'woothemes');
$cart_url = $woocommerce->cart->get_cart_url();
$cart_contents = sprintf(_n('%d produto', '%d produtos', $woocommerce->cart->cart_contents_count, 'woothemes'), $woocommerce->cart->cart_contents_count);
I'm briefly changing the website's language to English so you can have a look if you want to.
Oh, and I did try setting both menus, but at the time it had no effect.