How to use werc on this?

The most obvious impediment to running werc is that TuxFamily does not provide rc (yet?).
We could install it; however, finding web hosters that provide both classic CGI and rc may prove difficult; are you sure you want to go this way?
You could look for a similar tool relying on sh/bash (thus keeping only the dependency on CGI), or you could experiment with static sites generators.

Exection-wise, webserver-side, you can hardly find lighter than static files (well, ok, you can hardcode your pages inside the webserver configuration). Since werc uses Markdown by default, and assuming you do not want an invasive tool (language interpreter + dependencies + tool code), what about Hugo? https://gohugo.io/