The Universe main search is extremely powerful. It searches from your channels, posts, organisation users, Pages, Google Drive, Google Sites, Google Calendar and Gmail.
To get started just start typing and you'll see the first search predictions. The predictions have people, channels and pages.
If you want to do a wide search type something into the search bar and press enter. This will show you top results. By toggling the different sections you can see more results from the different sections.