It sounds like Wordpress might be a good fit for your project. Like anything, there is a learning curve, but with little web design experience you can get a site up quickly with it and then expand, customize and improve on it as you learn more.
BuddyPress is a plug-in you can then install into Wordpress to add social features such as activity streams, forums and individual user accounts.
Joomla is another great CMS platform. It is not as easy to use as Wordpress but offers endless variety and many rich components and modules (plug-ins) to create a rich community site.
These are both available as One-clicks here. Use the Custom installation method.