plugins

Take a look at my instructions here.  The program will appear as a plug-in under the Filter>Skylum menu:

@Test Screen Name, I don't think there are any true Photoshop plug-ins that are not compatible with Elements.  There may be some "plug-ins" that use actions that are not available in Elements.  The only one I can recall is related to removing recurring textures/patterns from scanned photos. 

(Neo is more of a full-featured program rather than a plug-in.  As I understand it, the developers are in Ukraine, so understandably support is currently somewhat limited.)

Ask the makers of the plug-in whether it is compatible. If they don't know or won't say, assume not. Most plug-in creators don't make or test for Elements, only Photoshop. (But if there's a free trial you could check it out).