In the top menu, between Worksheet and Story, you can find the following options for Dashboards:

Among those options, the most important one surely is Actions.... There is a focus on Actions in a later section. Format is also handy as you can configure the Dashboard color background, titles, and text objects. The Grid is a great new feature if, like me, you like when everything is properly aligned. You can decide whether to show the Grid, and how to configure its size. 

All the other options are either straightforward to understand and use (such as Export Image...) or just duplicates of option in different places (such as Device Layouts, Show Title, and Auto Update).

That's it for the basics, but you still have many things to learn about Dashboards! The next section is about building a Dashboard with one of the most significant divisions between Tableau users: Tiled or Floating.