install

Dear sir,

For my parish I made a small website (www.orthodox-amersfoort.nl) with RapidWeaver.
It would be nice to add a small forum to the site.
The activity closest to programming I ever dared was copy-pasting Freefind and a button into the sidebar.
I tried to install PunBB and failed.
I am completely at loss.
Is there a simple way how it can be done by a simple use like myself?
I know nothing about root directory et cetara.
Yours truly,
+Stephan Bakker