http://codex.simple-press.com/codex/plugins/using-plugins/

should get you started… (images are missing)

OK – so simply put, load the individual plugin folders to the sp-resources/forum-plugins folder then go to the plugins section in the forum admin and activate.  Might be worth writing that in the info on the download page 🙂

yes, upload them to that folder (assuming thats where you specified – it is the default) and activate on the forum plugins panel…

themes work similarily in sp-resources/forum-themes and the forum themes admin panel…