Yasnippet directory structure

Snippet directories are located in the variable yas-snippet-dirs, which by default has a single value of ~/emacs.d/snippets, for your personal snippets. You can find many snippet collections on the web, and as you add them to your setup you have to keep adding stuff to the yas-snippet-dirs variable.

;; keeping YASnippet defaults try out ~/Downloads/interesting-snippets
(setq yas-snippet-dirs (append yas-snippet-dirs
			       '("~/Downloads/interesting-snippets")))

Under each snippet folder are sub-folders named for the major-modes for which the snippets apply.