OS X El Capitan: Open folders in new Finder tabs or windows
When you open a folder in the Finder, the folder’s contents usually replace the current contents of the window. If you prefer, you can open a folder in a new tab or window.
Set folders to open in tabs or windows
In the Finder, choose Finder > Preferences, then click General.
Select or deselect “Open folders in tabs instead of new windows.”
Open folders in tabs or windows
Press the Command key while you double-click the folder.
The folder opens in a new tab or window, depending on your Finder preferences.
To open a new Finder window without opening a specific folder, choose File > New Finder Window or press Command-N.
Work with tabs
If all of your tabs aren’t visible, scroll through them.
When two or more tabs are open, click the Add button to open a new tab.
To close a tab, place the pointer over the tab, then click the Delete button .