How do I go about hosting a wordpress blog as a hidden service? Are there providers who will host it for me? Or will I have to configure it myself?
You can use one of these solutions:
-Real Hosting [http://hosting6iar5zo7c.onion/]: purchase a web space (you have to pay with bitcoin monthly or yearly) and you can also customize some letters of the onion domain. The basic service gives you 256MB of space.
-Prometheus_Hidden_Services [http://prometh5th5t5rfd.onion/]: with this you can run a virtual machine based in the dark web.
This one is free.
-Liberty’s Hackers [http://libertygb2nyeyay.onion/]
Post Scriptum: some of these links may be dead, last time I checked they worked. Of course the topic of your blog have to be something legal, otherwise these providers will shut your site.