See also: Using the path bar
To select a file in the Files sidebar, click on it.
To open a file from the Files sidebar, double-click on it.
To rename a file in the Files sidebar, click once on its name and don't move the mouse away for one full second. When the text input box appears, type the new name and press return.
To switch between local and remote files, use the switcher located at the bottom of the Files sidebar.
To access other file actions from the Files sidebar, control-click on selected File(s).