Clicking on a group won't affect what your Facebook friends see.  It just affects what you see on your home page.  Here's a procedure to limit status updates ("What's on Your Mind") so that some friends can't see them:

1. Go to "Settings" at the top of the page.
2. Select "Privacy Settings."
3. Click on "Profile."
4. Under "Status and Links," click "Edit Custom Settings."
5. Select "Only Friends" and "None of My Networks," and then under "Except These People," enter the names of friends or a group of friends that you don't want to see your status and links.