Good question! We don't have an own sidebar, but Outlook comes with an own one, which let's you view your to-dos side by side with your emails. To enable this, follow the steps below:
1. In your main Outlook window, click "View" (in the ribbon), "To-Do Bar" => "Tasks".
2. Now the task bar should appear right beside your preview pane. You can change the display options, e.g. if you want them to be separated by folder (list).
You can also create new tasks from the sidebar. To do this, right click in the sidebar and select "New Task". Make sure to use the "Save To" function, otherwise the to-do will end up in your main task folder (and not synced to any Wunderlist list).