I'd cut that landing page down to the bare essentials.
The site itself feels very complete, but without content it is impossible to understand what the point really is. I registered and as others mentioned, I had no clue what to do. The "what to do" drop down is great, but so much to read. I don't have the patience to read all that (and I want to help you), so I wouldn't expect a user to read it.
Regarding content; you need to champion a topic. Pick something you know that would relate to other people. If you can't think of something, do something technical.. The site can't be empty, and the things that people see must be current.
good luck, looks like a strong start