First: Move Forum Management and General Discussion to the bottom. Visitors should see your niche related forums first - such as networking support, etc. Anything general or off-topic always goes further down the page.
Second: What would make anyone want to come to your forum? What's unique about it? If I was searching for a computer forum, I wouldn't see any real purpose to sign-up to yours. There's no welcome message for guests, nothing that really seems to make you stand out.
Therefore, you need to implement a welcome message for your guests and think of some ideas that will make your forum worth signing-up to, instead of the other million computer forums out there.