Usually, the best way to get to know a place is to dive right in - maybe not comment right away, but read the entries of a community, read the entries of the people you find interesting. Eventually something will be written that you will find yourself wanting to respond to. Don't be afraid to do it! Even if it's a short note. Dreamwidth, like Live Journal is all about communication, and interaction. You don't get the interaction without the communication.

You can first start with your own interests: On your journal, for instance, you mention you run Linux on your home computer. There is a Linux community here linux4all, and many who list Linux as their interest. The first thing to do is to run a interest search using the term Linux as a search term.

I just did this, and there are four communities, as well as five pages of users, including several developers from Dreamwidth. (Who are a boisterous, funny, friendly bunch) You can do that with any interest you have, photography, literature, autism. Anything.

I'm fairly new to the whole paradigm of Live Journal/Dreamwidth as well. This would be my second year or so. So, I totally understand your feeling like you're out at sea in a boat without paddles. The trick is finding the paddles and learning how to row in the right direction, I guess.

I hope I have been of help.