You can change the content display language with Multilanguage widget, which is activated automatically when you activate the plugin if you have an active sidebar. If you have several active sidebars, the widget is added to the sidebar, which features a search widget. But if you do not have an active sidebar, you need to create it and add Multilanguage widget manually.
Also you can add Multilanguage Switcher via "shortcode". For that, open a post in the Edit mode, put the cursor to the appropriate place in your content and click "Add BWS Shortcode" button. Click "Insert" button and publish/update your post.
And finally, you can add Multilanguage Switcher to menus. Choose the necessary menu and click "Select" button. Then mark "Multilanguage switcher" checkbox and click "Add to Menu" button. After all, click "Save Menu" button.
In order to get more detailed information on the issue, check Multilanguage - User Guide.