How to keep intro page private form non logged in users

Sorry about the garbled title but in a nutshell, as my site is a school, I dont want strangers being able to see such things as groups, members etc without logging in. Currently my site: http://www.greatoaksschoolgo.co.uk displays too much information to browsers. I am using the BuddyPress social theme. Can anyone give me some simple steps on how to hide this information? Thanks