Here are the basics of how to use the plugin:

Use the natural vim navigation keys hjkl to navigate the files.
Press o to open the file in a new buffer or open/close directory.
Press t to open the file in a new tab.
Press i to open the file in a new horizontal split.
Press s to open the file in a new vertical split.
Press p to go to parent directory.
Press r to refresh the current directory.
All other keyboard shortcuts can be found by pressing ?. It will open a special help screen with the shortcut listings. Press ? again to get back to file tree.

To close the plugin execute the :NERDTreeClose command.

Typing :NERDTree and :NERDTreeClose all the time is really inconvenient. Therefore I have mapped the toggle command :NERDTreeToggle to the F2 key. This way I can quickly open and close Nerd Tree whenever I wish. You can also map it to F2 by putting map <F2> :NERDTreeToggle<CR> in your .vimrc file.

Basic shortcuts

NERDTree manual

Other