I know of Oracle, and have used it a very long time ago…
I support rhombus' suggestion, that you should come up with a new theme instead of using one of the built-in ones. If you don't know much about CSS (like me) then you can visit http://themes.wikidot.com for CSS themes that other Wikidot users have created :)
Also, to prevent the forums from looking empty, I usually start off with a maximum of 2-3 sections and expand only when it is absolutely necessary. Creating a lot of sections and trying to get everything organised from the beginning may seem like a smart thing to do, but it emphasises the fact that the website is new and that there is a minimal if not non-existent community behind it.
Thirdly, there are already a large number of Oracle support forums around, and similar programming websites that offer a small Oracle section for technical support. In a way, you're reinventing the wheel and creating yet another when so many of these forums already exist. You need to come up with something new as well that you can offer, based on what features Wikidot can give you. If you have something unique that other websites don't offer, people will revisit your website and the community will grow. If you only have a forum (instead of forum + unique feature) then people will see it as a new website that isn't worth returning to, at least not in the near future. Random visitors don't want to invest their time in building up a community if they're not sure that it will succeed.
Just my two cents… ;-)