After installing the latest version of Snap Art or Exposure, the plug-ins can be found in Photoshop’s menu Filter>Alien Skin.
In the past, we gave each product it’s own menu, such as Filter>Alien Skin Snap Art 2. We did that because our products consisted of many filters. Putting them all in one menu would have jumbled them together in one huge alphabetized list. These days we are moving toward single filter products, and we will be moving them into Filter>Alien Skin as we update them.
There could be other reasons why you do not see your plugin. Here are a couple other articles that may help you, if this one does not answer your questions. There is a lot of information, so we have them split up into several articles.