OFFLINE

This is probably something extremely simple to do but I am at a loss at how to do it.  Would appreciate your assistance.  Every time I log on to Facebook, I am overwhelmed with posting from several groups.  I have not signed up to make them my friend.  At one time in the past, I have contacted them about a poll or something of this nature.  One of the groups is called "Geico Best of College Football".  Another is called "Give2TheTroops, Inc.  My Facebook page has been taken over by their postings.  Any idea how I go about stop receiving all of these postings?  Your assistance is greatly appreciated.