how to add channels/private groups?

I've recently installed elgg and am enjoying figuring it all out.  I'm planning to use it for online (knitting) classes, so I'm trying to figure out how to set up channels as illustrated in this elgg blog post (  I'm not having luck in figuring it out, though!  

So, I need to be able to have different groups (channels), each with their own blog/videos/comment wall, and that only that group has access to.  The access will be for a one month periods (the length of the class) and then a new group will come in and replace the previous class.  What's the best way to accomplish this?