Plugins Question (PSP 8)

I just downloaded some zipped plug-ins, but I don't know how to install them. The instructions say that you have to put them into your host's plug-in folder, but I can't see PSP 8's one and it said on the site that they used PSP 8 so it must be right... can anyone help with what the folder is called or something. I checked the memories but couldn't find anything.

Also, once I've done that, how do I access them in PSP 8?