I use pathogen to manage vim plugins, and it is especially useful in conjunction with a public source control system like github. Once you have pathogen installed simply pull the NerdTree Github project to your vim plugins directory.
git clone git://github.com/scrooloose/nerdtree.git
Next add a shortcut to make opening your NERDTree more convenient by adding the following to your vim config file (~/.vimrc)
" Give a shortcut key to NERD Tree
map <F2> :NERDTreeToggle<CR>
Now fire up your MacVim, open a window, and press (fn+F2).
With NerdTree now started, the following commands should get you going:
- Use the natural vim navigation keys hjkl to navigate the files, or just the arrow keys
- 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.