Before I start, I've done a search for similar posts, but found nothing relevant, though lots of people must have this basic problem.

I've installed as per instructions, and the basic forum works, but there's no graphics.
See http://www.matbennion.com/forum/cgi-bin/forum/Blah.pl

So presumably there's a problem with the paths.  During installation, I got an error message telling me that the paths were wrong, so I put in a relative path (../../blahdocs) and the message went away, but then the forum didn't work at all (the error message told me I had to use an absolute path).

So I ran perlinfo, found that the absolute path to my web host area is /home/vhosts/mjb2962-2086140/, and updated Settings.pl accordingly.  Still didn't work, so I tried moving blahdocs into the cgi-bin directory, but it still didn't work.

Just to make sure there wasn't a problem with my web hosting, I installed yaBB, and it worked fine after I'd given it the path to the public_html directory.  See http://www.matbennion.com/yabb2/cgi-bin/yabb2/YaBB.pl

Any ideas?

That looks like the path to the style sheet is not correct...

Have you got a seperate blahdocs folder ?

http://www.matbennion.com/blahdocs

Well, I put blahdocs at the root, used perlinfo to double-check the path, checked this and that, and it sprang into life.

Nothing I hadn't done already really.

Thanks for your comment, it spurred me on!