Hi all, apologies for the belated response, instructions below.

First, please note the following:
a) You must be an active member to join a community i.e. have TheGoodBlogs widget on your blog.
b) At present, the community has to approve you. We will be changing the way communities work in the future.

For now, follow these steps:

1) Login to the goodblogs http://www.thegoodblogs.com/user/login
2) Click the "My Communities icon" (http://www.thegoodblogs.com/communities)
3) Click on "All communities", you will see a list of all communities
4) Use the filter tool to narrow the list of communities
5) Click on the community of interest, you will see the community details and blogs that are part of the community
6) Click on the " I Would Like To Join This Community" link. This will send a message to the community owner.
7) When you are approved, you will received a private message.